10-Q

Table of Contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

☒    QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2023

or

☐    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                    to                    

Name of Registrant, State of Incorporation, Address of Principal Executive Offices, Telephone Number, Commission File Number, IRS Employer Identification Number

ALLIANT ENERGY CORPORATION

(a Wisconsin Corporation)

4902 N. Biltmore Lane

Madison, Wisconsin 53718

Telephone (608) 458-3311

Commission File Number - 1-9894

IRS Employer Identification Number - 39-1380265

INTERSTATE POWER & LIGHT COMPANY

(an Iowa corporation)

Alliant Energy Tower

Cedar Rapids, Iowa 52401

Telephone (319) 786-4411

Commission File Number - 1-4117

IRS Employer Identification Number - 42-0331370

WISCONSIN POWER & LIGHT COMPANY

(a Wisconsin corporation)

4902 N. Biltmore Lane

Madison, Wisconsin 53718

Telephone (608) 458-3311

Commission File Number - 0-337

IRS Employer Identification Number - 39-0714890

This combined Form 10-Q is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contained in the Form 10-Q relating to Interstate Power and Light Company and Wisconsin Power and Light Company is filed by each such registrant on its own behalf. Each of Interstate Power and Light Company and Wisconsin Power and Light Company makes no representation as to information relating to registrants other than itself.

Securities registered pursuant to Section 12(b) of the Act:

Alliant Energy Corporation, Common Stock, $0.01 Par Value, Trading Symbol LNT, Nasdaq Global Select Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Alliant Energy Corporation - Yes ☒ No ☐

Interstate Power and Light Company - Yes ☒ No ☐

Wisconsin Power and Light Company - Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Alliant Energy Corporation - Yes ☒ No ☐

Interstate Power and Light Company - Yes ☒ No ☐

Wisconsin Power and Light Company - Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Alliant Energy Corporation - Large Accelerated Filer ☒ Accelerated Filer ☐ Non-accelerated Filer ☐ Smaller Reporting Company ☐ Emerging Growth Company ☐

Interstate Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐

Wisconsin Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

Alliant Energy Corporation ☐

Interstate Power and Light Company ☐

Wisconsin Power and Light Company ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Alliant Energy Corporation - Yes ☐ No ☒

Interstate Power and Light Company - Yes ☐ No ☒

Wisconsin Power and Light Company - Yes ☐ No ☒

Number of shares outstanding of each class of common stock as of September 30, 2023:

Alliant Energy Corporation, Common Stock, $0.01 par value, 255,179,087 shares outstanding

Interstate Power and Light Company, Common Stock, $2.50 par value, 13,370,788 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)

Wisconsin Power and Light Company, Common Stock, $5 par value, 13,236,601 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)

Table of Contents

TABLE OF CONTENTS

	Page
Definitions	1
Forward-looking Statements	1
Part I. Financial Information	3
Item 1. Condensed Consolidated Financial Statements (Unaudited)	3
Alliant Energy Corporation	3
Interstate Power and Light Company	6
Wisconsin Power and Light Company	9
Combined Notes to Condensed Consolidated Financial Statements	12
1. Summary of Significant Accounting Policies	12
2. Regulatory Matters	12
3. Property, Plant and Equipment	13
4. Receivables	13
5. Investments	14
6. Common Equity	14
7. Debt	16
8. Revenues	18
9. Income Taxes	18
10. Benefit Plans	19
11. Derivative Instruments	20
12. Fair Value Measurements	21
13. Commitments and Contingencies	24
14. Segments of Business	25
15. Related Parties	27
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations	27
Item 3. Quantitative and Qualitative Disclosures About Market Risk	37
Item 4. Controls and Procedures	37
Part II. Other Information	37
Item 1. Legal Proceedings	37
Item 1A. Risk Factors	37
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds	37
Item 5. Other Information	37
Item 6. Exhibits	38
Signatures	38

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DEFINITIONS

The following abbreviations or acronyms used in this report are defined below:

Abbreviation or Acronym	Definition	Abbreviation or Acronym	Definition
2022 Form 10-K	Combined Annual Report on Form 10-K filed by Alliant Energy, IPL and WPL for the year ended Dec. 31, 2022	IUB	Iowa Utilities Board
AEF	Alliant Energy Finance, LLC	MDA	Management’s Discussion and Analysis of Financial Condition and Results of Operations
AFUDC	Allowance for funds used during construction	MISO	Midcontinent Independent System Operator, Inc.
Alliant Energy	Alliant Energy Corporation	MW	Megawatt
ATC	American Transmission Company LLC	MWh	Megawatt-hour
ATC Holdings	Interest in American Transmission Company LLC and ATC Holdco LLC	N/A	Not applicable
Corporate Services	Alliant Energy Corporate Services, Inc.	Note(s)	Combined Notes to Condensed Consolidated Financial Statements
Dth	Dekatherm	OPEB	Other postretirement benefits
EGU	Electric generating unit	PPA	Purchased power agreement
EPA	U.S. Environmental Protection Agency	PSCW	Public Service Commission of Wisconsin
EPS	Earnings per weighted average common share	SEC	Securities and Exchange Commission
Financial Statements	Condensed Consolidated Financial Statements	U.S.	United States of America
FTR	Financial transmission right	West Riverside	West Riverside Energy Center and Solar Facility
GAAP	U.S. generally accepted accounting principles	Whiting Petroleum	Whiting Petroleum Corporation
IPL	Interstate Power and Light Company	WPL	Wisconsin Power and Light Company

FORWARD-LOOKING STATEMENTS

Statements contained in this report that are not of historical fact are forward-looking statements intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified as such because the statements include words such as “may,” “believe,” “expect,” “anticipate,” “plan,” “project,” “will,” “projections,” “estimate,” or other words of similar import. Similarly, statements that describe future financial performance or plans or strategies are forward-looking statements. Such forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. Some, but not all, of the risks and uncertainties of Alliant Energy, IPL and WPL that could materially affect actual results include:

•the direct or indirect effects resulting from cybersecurity incidents or attacks on Alliant Energy, IPL, WPL, or their suppliers, contractors and partners, or responses to such incidents;

•the impact of customer- and third party-owned generation, including alternative electric suppliers, in IPL’s and WPL’s service territories on system reliability, operating expenses and customers’ demand for electricity;

•the impact of energy efficiency, franchise retention and customer disconnects on sales volumes and margins;

•the impact that price changes may have on IPL’s and WPL’s customers’ demand for electric, gas and steam services and their ability to pay their bills;

•inflation and higher interest rates;

•changes in the price of delivered natural gas, transmission, purchased electricity and delivered coal, particularly during elevated market prices, and any resulting changes to counterparty credit risk, due to shifts in supply and demand caused by market conditions, regulations and MISO’s seasonal resource adequacy process;

•IPL’s and WPL’s ability to obtain adequate and timely rate relief to allow for, among other things, the recovery of and/or the return on costs, including fuel costs, operating costs, transmission costs, capacity costs, deferred expenditures, deferred tax assets, tax expense, interest expense, capital expenditures, and remaining costs related to EGUs that may be permanently closed and certain other retired assets, decreases in sales volumes, earning their authorized rates of return, and the payments to their parent of expected levels of dividends;

•the ability to obtain regulatory approval for construction projects with acceptable conditions;

•the ability to complete construction of renewable generation and storage projects by planned in-service dates and within the cost targets set by regulators due to cost increases of and access to materials, equipment and commodities, which could result from tariffs, duties or other assessments, such as any additional tariffs resulting from U.S. Department of Commerce investigations into and any decisions made regarding the sourcing of solar project materials and equipment from certain countries, labor issues or supply shortages, the ability to successfully resolve warranty issues or contract disputes, the ability to achieve the expected level of tax benefits based on tax guidelines, project costs and the level of electricity output generated by qualifying generating facilities, and the ability to efficiently utilize the renewable generation and storage project tax benefits for the benefit of customers;

•the ability to utilize tax credits generated to date, and those that may be generated in the future, before they expire, as well as the ability to transfer tax credits that may be generated in the future at adequate pricing;

•disruptions to ongoing operations and the supply of materials, services, equipment and commodities needed to construct solar generation, battery storage and electric and gas distribution projects, which may result from geopolitical issues, supplier manufacturing constraints, labor issues or transportation issues, and thus affect the ability to meet capacity requirements and result in increased capacity expense;

•the future development of technologies related to electrification, and the ability to reliably store and manage electricity;

•federal and state regulatory or governmental actions, including the impact of legislation, and regulatory agency orders;

•the impacts of changes in the tax code, including tax rates, minimum tax rates, adjustments made to deferred tax assets and liabilities, and changes impacting the availability of renewable tax credits;

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•employee workforce factors, including the ability to hire and retain employees with specialized skills, impacts from employee retirements, changes in key executives, ability to create desired corporate culture, collective bargaining agreements and negotiations, work stoppages or restructurings;

•disruptions in the supply and delivery of natural gas, purchased electricity and coal;

•changes to the creditworthiness of, or performance of obligations by, counterparties with which Alliant Energy, IPL and WPL have contractual arrangements, including participants in the energy markets and fuel suppliers and transporters;

•the impact of penalties or third-party claims related to, or in connection with, a failure to maintain the security of personally identifiable information, including associated costs to notify affected persons and to mitigate their information security concerns;

•impacts that terrorist attacks may have on Alliant Energy’s, IPL’s and WPL’s operations and recovery of costs associated with restoration activities, or on the operations of Alliant Energy’s investments;

•any material post-closing payments related to any past asset divestitures, including the sale of Whiting Petroleum, which could result from, among other things, indemnification agreements, warranties, guarantees or litigation;

•weather effects on results of utility operations;

•continued access to the capital markets on competitive terms and rates, and the actions of credit rating agencies;

•changes to MISO’s resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements that may impact how and when new and existing generating facilities, including IPL’s and WPL’s additional solar generation, may be accredited with energy capacity, and may require IPL and WPL to adjust their current resource plans, to add resources to meet the requirements of MISO’s process, or procure capacity in the market whereby such costs might not be recovered in rates;

•issues associated with environmental remediation and environmental compliance, including compliance with all environmental and emissions permits and future changes in environmental laws and regulations, including changes to the Coal Combustion Residuals Rule, Cross-State Air Pollution Rule and federal, state or local regulations for greenhouse gases emissions reductions from new and existing fossil-fueled EGUs under the Clean Air Act, and litigation associated with environmental requirements;

•increased pressure from customers, investors and other stakeholders to more rapidly reduce greenhouse gases emissions;

•the ability to defend against environmental claims brought by state and federal agencies, such as the EPA and state natural resources agencies, or third parties, such as the Sierra Club, and the impact on operating expenses of defending and resolving such claims;

•the direct or indirect effects resulting from breakdown or failure of equipment in the operation of electric and gas distribution systems, such as mechanical problems and explosions or fires, and compliance with electric and gas transmission and distribution safety regulations, including regulations promulgated by the Pipeline and Hazardous Materials Safety Administration;

•issues related to the availability and operations of EGUs, including start-up risks, breakdown or failure of equipment, availability of warranty coverage and successful resolution of warranty issues or contract disputes for equipment breakdowns or failures, performance below expected or contracted levels of output or efficiency, operator error, employee safety, transmission constraints, compliance with mandatory reliability standards and risks related to recovery of resulting incremental operating, fuel-related and capital costs through rates;

•impacts that excessive heat, excessive cold, storms, wildfires, or natural disasters may have on Alliant Energy’s, IPL’s and WPL’s operations and construction activities, and recovery of costs associated with restoration activities, or on the operations of Alliant Energy’s investments;

•the direct or indirect effects resulting from the ongoing novel coronavirus (COVID-19) pandemic and the spread of variant strains;

•Alliant Energy’s ability to sustain its dividend payout ratio goal;

•changes to costs of providing benefits and related funding requirements of pension and OPEB plans due to the market value of the assets that fund the plans, economic conditions, financial market performance, interest rates, timing and form of benefits payments, life expectancies and demographics;

•material changes in employee-related benefit and compensation costs, including settlement losses related to pension plans;

•risks associated with operation and ownership of non-utility holdings;

•changes in technology that alter the channels through which customers buy or utilize Alliant Energy’s, IPL’s or WPL’s products and services;

•impacts on equity income from unconsolidated investments from changes in valuations of the assets held, as well as potential changes to ATC’s authorized return on equity;

•impacts of IPL’s future tax benefits from Iowa rate-making practices, including deductions for repairs expenditures, allocation of mixed service costs and state depreciation, and recoverability of the associated regulatory assets from customers, when the differences reverse in future periods;

•current or future litigation, regulatory investigations, proceedings or inquiries;

•reputational damage from negative publicity, protests, fines, penalties and other negative consequences resulting in regulatory and/or legal actions;

•the effect of accounting standards issued periodically by standard-setting bodies;

•the ability to successfully complete tax audits and changes in tax accounting methods with no material impact on earnings and cash flows; and

•other factors listed in MDA and Risk Factors in Item 1A in the 2022 Form 10-K.

Alliant Energy, IPL and WPL each assume no obligation, and disclaim any duty, to update the forward-looking statements in this report, except as required by law.

Available Information. Alliant Energy routinely posts important information on its website and considers the Investors section of its website, www.alliantenergy.com/investors, a channel of distribution for material information. Information contained on Alliant Energy’s website is not incorporated herein.

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PART I. FINANCIAL INFORMATION

ITEM 1. CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

	For the Three Months		For the Nine Months
	Ended September 30,		Ended September 30,
	2023	2022	2023	2022
	(in millions, except per share amounts)
Revenues:
Electric utility	$995	$1,039	$2,562	$2,624
Gas utility	47	62	400	418
Other utility	13	11	38	35
Non-utility	22	23	66	70
Total revenues	1,077	1,135	3,066	3,147
Operating expenses:
Electric production fuel and purchased power	231	274	553	633
Electric transmission service	154	157	438	428
Cost of gas sold	12	26	226	242
Other operation and maintenance	160	172	499	492
Depreciation and amortization	170	169	503	501
Taxes other than income taxes	28	28	87	82
Total operating expenses	755	826	2,306	2,378
Operating income	322	309	760	769
Other (income) and deductions:
Interest expense	99	83	289	235
Equity income from unconsolidated investments, net	(14)	(5)	(45)	(37)
Allowance for funds used during construction	(28)	(10)	(71)	(34)
Other	1	—	2	—
Total other (income) and deductions	58	68	175	164
Income before income taxes	264	241	585	605
Income tax expense	5	14	3	26
Net income attributable to Alliant Energy common shareowners	$259	$227	$582	$579
Weighted average number of common shares outstanding:
Basic	253.5	251.0	252.1	250.8
Diluted	253.8	251.3	252.4	251.1
Earnings per weighted average common share attributable to Alliant Energy common shareowners (basic and diluted)	$1.02	$0.90	$2.31	$2.31

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

	September 30, 2023	December 31, 2022
	(in millions, except per share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents	$206	$20
Accounts receivable, less allowance for expected credit losses	486	516
Production fuel, at weighted average cost	44	53
Gas stored underground, at weighted average cost	87	132
Materials and supplies, at weighted average cost	196	140
Regulatory assets	179	166
Other	174	223
Total current assets	1,372	1,250
Property, plant and equipment, net	16,633	16,247
Investments:
ATC Holdings	380	358
Other	214	201
Total investments	594	559
Other assets:
Regulatory assets	2,090	1,880
Deferred charges and other	215	227
Total other assets	2,305	2,107
Total assets	$20,904	$20,163

LIABILITIES AND EQUITY
Current liabilities:
Current maturities of long-term debt	$409	$408
Commercial paper	451	642
Other short-term borrowings	50	—
Accounts payable	604	756
Regulatory liabilities	92	206
Other	329	351
Total current liabilities	1,935	2,363
Long-term debt, net (excluding current portion)	8,429	7,668
Other liabilities:
Deferred tax liabilities	1,913	1,943
Regulatory liabilities	1,095	1,118
Pension and other benefit obligations	262	277
Other	544	518
Total other liabilities	3,814	3,856
Commitments and contingencies (Note 13)
Equity:
Alliant Energy Corporation common equity:
Common stock - $0.01 par value - 480,000,000 shares authorized; 255,179,087 and 251,134,966 shares outstanding	3	3
Additional paid-in capital	2,982	2,777
Retained earnings	3,750	3,509
Accumulated other comprehensive income	4	—
Shares in deferred compensation trust - 393,781 and 402,134 shares at a weighted average cost of $34.13 and $32.63 per share	(13)	(13)
Total Alliant Energy Corporation common equity	6,726	6,276
Total liabilities and equity	$20,904	$20,163

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

	For the Nine Months
	Ended September 30,
	2023	2022
	(in millions)
Cash flows from operating activities:
Net income	$582	$579
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	503	501
Equity component of allowance for funds used during construction	(53)	(25)
Other	15	25
Other changes in assets and liabilities:
Accounts receivable	(279)	(425)
Materials and supplies	(56)	(13)
Derivative assets	102	(184)
Regulatory assets	40	(102)
Accounts payable	(91)	90
Derivative liabilities	(13)	89
Regulatory liabilities	(126)	89
Other	(2)	(139)
Net cash flows from operating activities	622	485
Cash flows used for investing activities:
Construction and acquisition expenditures:
Utility business	(1,201)	(873)
Other	(92)	(69)
Cash receipts on sold receivables	306	358
Proceeds from sales of partial ownership interest in West Riverside	120	—
Other	(85)	(15)
Net cash flows used for investing activities	(952)	(599)
Cash flows from financing activities:
Common stock dividends	(341)	(322)
Proceeds from issuance of common stock, net	201	19
Proceeds from issuance of long-term debt	1,158	1,238
Payments to retire long-term debt	(404)	(379)
Net change in commercial paper and other short-term borrowings	(141)	(132)
Contributions from noncontrolling interest	—	29
Distributions to noncontrolling interest	—	(29)
Other	42	(3)
Net cash flows from financing activities	515	421
Net increase in cash, cash equivalents and restricted cash	185	307
Cash, cash equivalents and restricted cash at beginning of period	24	40
Cash, cash equivalents and restricted cash at end of period	$209	$347
Supplemental cash flows information:
Cash paid during the period for:
Interest	($280)	($220)
Income taxes, net	($6)	($7)
Significant non-cash investing and financing activities:
Accrued capital expenditures	$287	$403
Beneficial interest obtained in exchange for securitized accounts receivable	$236	$248

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

	For the Three Months		For the Nine Months
	Ended September 30,		Ended September 30,
	2023	2022	2023	2022
	(in millions)
Revenues:
Electric utility	$551	$596	$1,370	$1,438
Gas utility	31	33	224	224
Steam and other	12	11	36	34
Total revenues	594	640	1,630	1,696
Operating expenses:
Electric production fuel and purchased power	99	140	213	290
Electric transmission service	115	115	316	303
Cost of gas sold	12	14	127	126
Other operation and maintenance	84	90	264	260
Depreciation and amortization	97	95	288	285
Taxes other than income taxes	14	15	43	43
Total operating expenses	421	469	1,251	1,307
Operating income	173	171	379	389
Other (income) and deductions:
Interest expense	38	37	113	111
Allowance for funds used during construction	(6)	(3)	(13)	(8)
Other	2	(1)	3	(2)
Total other (income) and deductions	34	33	103	101
Income before income taxes	139	138	276	288
Income tax benefit	(31)	(16)	(55)	(39)
Net income	$170	$154	$331	$327

Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of IPL’s common stock outstanding during the periods presented.

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

	September 30, 2023	December 31, 2022
	(in millions, except per share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents	$188	$15
Accounts receivable, less allowance for expected credit losses	258	259
Production fuel, at weighted average cost	22	23
Gas stored underground, at weighted average cost	40	60
Materials and supplies, at weighted average cost	111	83
Regulatory assets	86	85
Other	70	93
Total current assets	775	618
Property, plant and equipment, net	8,042	8,046
Other assets:
Regulatory assets	1,504	1,301
Deferred charges and other	106	110
Total other assets	1,610	1,411
Total assets	$10,427	$10,075

LIABILITIES AND EQUITY
Current liabilities:
Accounts payable	$255	$239
Accounts payable to associated companies	59	28
Accrued taxes	68	52
Accrued interest	41	35
Regulatory liabilities	63	114
Other	84	113
Total current liabilities	570	581
Long-term debt, net	3,944	3,646
Other liabilities:
Deferred tax liabilities	987	1,047
Regulatory liabilities	592	640
Pension and other benefit obligations	59	62
Other	286	291
Total other liabilities	1,924	2,040
Commitments and contingencies (Note 13)
Equity:
Interstate Power and Light Company common equity:
Common stock - $2.50 par value - 24,000,000 shares authorized; 13,370,788 shares outstanding	33	33
Additional paid-in capital	2,867	2,807
Retained earnings	1,089	968
Total Interstate Power and Light Company common equity	3,989	3,808
Total liabilities and equity	$10,427	$10,075

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

	For the Nine Months
	Ended September 30,
	2023	2022
	(in millions)
Cash flows from operating activities:
Net income	$331	$327
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	288	285
Deferred tax benefit and tax credits	(17)	(24)
Other	(6)	(8)
Other changes in assets and liabilities:
Accounts receivable	(306)	(397)
Derivative assets	53	(118)
Regulatory assets	55	18
Accounts payable	(45)	71
Derivative liabilities	(25)	62
Regulatory liabilities	(90)	61
Deferred income taxes	(44)	(30)
Other	(3)	(81)
Net cash flows from operating activities	191	166
Cash flows from (used for) investing activities:
Construction and acquisition expenditures	(427)	(269)
Cash receipts on sold receivables	306	358
Other	(56)	(5)
Net cash flows from (used for) investing activities	(177)	84
Cash flows from (used for) financing activities:
Common stock dividends	(210)	(240)
Capital contributions from parent	60	—
Proceeds from issuance of long-term debt	296	—
Other	13	1
Net cash flows from (used for) financing activities	159	(239)
Net increase in cash, cash equivalents and restricted cash	173	11
Cash, cash equivalents and restricted cash at beginning of period	15	34
Cash, cash equivalents and restricted cash at end of period	$188	$45
Supplemental cash flows information:
Cash (paid) refunded during the period for:
Interest	($107)	($111)
Income taxes, net	$36	$33
Significant non-cash investing and financing activities:
Accrued capital expenditures	$108	$43
Beneficial interest obtained in exchange for securitized accounts receivable	$236	$248

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

	For the Three Months		For the Nine Months
	Ended September 30,		Ended September 30,
	2023	2022	2023	2022
	(in millions)
Revenues:
Electric utility	$444	$443	$1,192	$1,186
Gas utility	16	29	176	194
Other	1	—	2	1
Total revenues	461	472	1,370	1,381
Operating expenses:
Electric production fuel and purchased power	132	134	341	343
Electric transmission service	39	42	122	125
Cost of gas sold	—	13	99	117
Other operation and maintenance	64	70	197	193
Depreciation and amortization	71	71	208	211
Taxes other than income taxes	13	11	40	35
Total operating expenses	319	341	1,007	1,024
Operating income	142	131	363	357
Other (income) and deductions:
Interest expense	38	31	110	86
Allowance for funds used during construction	(22)	(7)	(58)	(26)
Other	(2)	—	(3)	—
Total other (income) and deductions	14	24	49	60
Income before income taxes	128	107	314	297
Income tax expense	21	16	47	50
Net income	$107	$91	$267	$247

Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of WPL’s common stock outstanding during the periods presented.

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

	September 30, 2023	December 31, 2022
	(in millions, except per share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents	$16	$5
Accounts receivable, less allowance for expected credit losses	214	244
Production fuel, at weighted average cost	21	29
Gas stored underground, at weighted average cost	47	73
Materials and supplies, at weighted average cost	82	54
Regulatory assets	93	81
Prepaid gross receipts tax	36	42
Other	50	60
Total current assets	559	588
Property, plant and equipment, net	8,085	7,722
Other assets:
Regulatory assets	586	579
Deferred charges and other	71	98
Total other assets	657	677
Total assets	$9,301	$8,987

LIABILITIES AND EQUITY
Current liabilities:
Commercial paper	$120	$290
Accounts payable	281	456
Regulatory liabilities	29	92
Other	117	111
Total current liabilities	547	949
Long-term debt, net	3,069	2,770
Other liabilities:
Deferred tax liabilities	796	789
Regulatory liabilities	503	478
Pension and other benefit obligations	128	140
Other	393	370
Total other liabilities	1,820	1,777
Commitments and contingencies (Note 13)
Equity:
Wisconsin Power and Light Company common equity:
Common stock - $5 par value - 18,000,000 shares authorized; 13,236,601 shares outstanding	66	66
Additional paid-in capital	2,478	2,233
Retained earnings	1,321	1,192
Total Wisconsin Power and Light Company common equity	3,865	3,491
Total liabilities and equity	$9,301	$8,987

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

	For the Nine Months
	Ended September 30,
	2023	2022
	(in millions)
Cash flows from operating activities:
Net income	$267	$247
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	208	211
Equity component of allowance for funds used during construction	(43)	(19)
Other	5	23
Other changes in assets and liabilities:
Derivative assets	55	(66)
Regulatory assets	(16)	(120)
Accounts payable	(55)	5
Regulatory liabilities	(37)	28
Other	53	(30)
Net cash flows from operating activities	437	279
Cash flows used for investing activities:
Construction and acquisition expenditures	(774)	(604)
Proceeds from sales of partial ownership interest in West Riverside	120	—
Other	(26)	(8)
Net cash flows used for investing activities	(680)	(612)
Cash flows from financing activities:
Common stock dividends	(138)	(133)
Capital contributions from parent	245	420
Proceeds from issuance of long-term debt	297	588
Net change in commercial paper	(170)	(236)
Contributions from noncontrolling interest	—	29
Distributions to noncontrolling interest	—	(29)
Other	20	(9)
Net cash flows from financing activities	254	630
Net increase in cash, cash equivalents and restricted cash	11	297
Cash, cash equivalents and restricted cash at beginning of period	5	2
Cash, cash equivalents and restricted cash at end of period	$16	$299
Supplemental cash flows information:
Cash paid during the period for:
Interest	($106)	($78)
Income taxes, net	($63)	($51)
Significant non-cash investing and financing activities:
Accrued capital expenditures	$172	$355

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

INTERSTATE POWER AND LIGHT COMPANY

WISCONSIN POWER AND LIGHT COMPANY

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.

In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

NOTE 1(b) Cash and Cash Equivalents - At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.

NOTE 2. REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Tax-related - Refer to Note 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2023.

Assets retired early and Asset retirement obligations - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset (assets retired early) on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of September 30, 2023 was $221 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. In September 2023, the Federal Energy Regulatory Commission approved continued recovery of the remaining net book value of Lansing from IPL’s wholesale customers. IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period includes a request for continued recovery of the remaining net book value of Lansing through 2037. In addition, IPL reclassified the remaining net book value of the associated AROs from property, plant and equipment to a regulatory asset (AROs) on Alliant Energy’s and IPL’s balance sheets.

Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

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Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and nine months ended September 30, 2023.

NOTE 3. PROPERTY, PLANT AND EQUIPMENT

In March 2023 and June 2023, Madison Gas and Electric Company and WEC Energy Group, Inc., respectively, acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interest in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements for the nine months ended September 30, 2023. As a result of these transactions, WPL’s undivided current ownership interest in West Riverside is 73.8%.

NOTE 4. RECEIVABLES

NOTE 4(a) - Accounts Receivable - For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

NOTE 4(b) - Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. In March 2023, IPL amended and extended through March 2024 the purchase commitment from the third party to which it sells its receivables. The limit on cash proceeds fluctuates between $5 million and $110 million, which IPL may change periodically throughout the year. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of September 30, 2023, IPL had $109 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Maximum outstanding aggregate cash proceeds	$94	$36	$110	$66
Average outstanding aggregate cash proceeds	46	3	68	8

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

	September 30, 2023	December 31, 2022
Customer accounts receivable	$161	$145
Unbilled utility revenues	88	132
Other receivables	1	—
Receivables sold to third party	250	277
Less: cash proceeds	1	80
Deferred proceeds	249	197
Less: allowance for expected credit losses	13	12
Fair value of deferred proceeds	$236	$185

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As of September 30, 2023, outstanding receivables past due under the Receivables Agreement were $18 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Collections	$616	$670	$1,720	$1,731
Write-offs, net of recoveries	5	3	9	6

Effective October 2023, the limit on cash proceeds under the Receivables Agreement is $5 million.

NOTE 5. INVESTMENTS

Unconsolidated Equity Investments - Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC Holdings	($12)	($7)	($37)	($29)
Other	(2)	2	(8)	(8)
	($14)	($5)	($45)	($37)

NOTE 6. COMMON EQUITY

Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2023	251,134,966
At-the-market offering program	3,569,937
Shareowner Direct Plan	339,850
Equity-based compensation plans	134,334
Shares outstanding, September 30, 2023	255,179,087

At-the-Market Offering Program - In December 2022, Alliant Energy filed a prospectus supplement under which it may sell up to $225 million of its common stock through an at-the-market offering program. As of September 30, 2023, Alliant Energy issued 3,569,937 shares of common stock through this program and received cash proceeds of $183 million, net of $2 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes.

Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

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Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

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WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

NOTE 7. DEBT

NOTE 7(a) Short-term Debt - In March 2023, Alliant Energy, IPL and WPL extended their single credit facility agreement, which currently expires in December 2027, and reallocated credit facility capacity amounts to $450 million for Alliant Energy at the parent company level, $250 million for IPL and $300 million for WPL, within the $1 billion total commitment. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

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In January 2023, AEF received $50 million of proceeds from its December 2022 term loan credit agreement, which was classified as “Other short-term borrowings” on Alliant Energy’s balance sheet as of September 30, 2023.

NOTE 7(b) Long-term Debt - In September 2023, IPL issued $300 million of 5.70% senior debentures due 2033. The net proceeds from IPL’s issuance were used to reduce cash amounts received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt, for general corporate purposes and/or were placed in money market fund investments. In June 2023, AEF retired its $400 million 3.75% senior notes. In March 2023, WPL issued $300 million of 4.95% debentures due 2033. WPL’s debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of its solar EGUs.

Convertible Senior Notes - In March 2023, Alliant Energy issued $575 million of 3.875% convertible senior notes (the Notes), which are senior unsecured obligations, and used the net proceeds from the issuance for general corporate purposes. The Notes will mature on March 15, 2026 unless earlier converted or repurchased, and no sinking fund is provided for the Notes. Alliant Energy may not redeem the Notes prior to the maturity date. Holders may convert their Notes at their option at any time prior to the close of business on the business day immediately preceding December 15, 2025 only under the following circumstances:

•during any calendar quarter commencing after the calendar quarter ending on June 30, 2023 (and only during such calendar quarter), if the last reported sale price of Alliant Energy’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day during such period;

•during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price (as defined in the related Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of Alliant Energy’s common stock and the conversion rate on each such trading day; or

•upon the occurrence of specified corporate events.

On or after December 15, 2025 until the close of business on the business day immediately preceding the maturity date, holders may convert all or any portion of their Notes at any time, regardless of the foregoing circumstances. Upon conversion of the Notes, Alliant Energy will pay cash up to the aggregate principal amount of the Notes to be converted and pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at its election, in respect of the remainder, if any, of its conversion obligation in excess of the aggregate principal amount of the Notes being converted.

The initial conversion rate is 15.5461 shares of common stock per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $64.32 per share of Alliant Energy’s common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, Alliant Energy will, in certain circumstances, increase the conversion rate for a holder who elects to convert its Notes in connection with such a corporate event.

If Alliant Energy undergoes a fundamental change (as defined in the related Indenture), then, subject to certain conditions, holders of the Notes may require Alliant Energy to repurchase for cash all or any portion of its Notes at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

As of September 30, 2023, the conditions allowing holders of the Notes to convert their Notes were not met, and as a result, the Notes were classified as “Long-term debt, net” on Alliant Energy’s balance sheet. As of September 30, 2023, the net carrying amount of the Notes was $567 million, with unamortized debt issuance costs of $8 million, and the estimated fair value (Level 2) of the Notes was $556 million. As of September 30, 2023, there were no shares of Alliant Energy’s common stock related to the potential conversion of the Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the Notes.

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NOTE 8. REVENUES

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

NOTE 9. INCOME TAXES

Income Tax Rates - Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

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	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Deferred Tax Assets and Liabilities -

Carryforwards - At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

Iowa Tax Reform - Pursuant to Iowa tax reform enacted in 2022, in September 2023, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 7.1%, effective January 1, 2024. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2024, which resulted in a $73 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a corresponding decrease in their deferred tax liabilities in the third quarter of 2023. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2024, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and an increase in deferred tax liabilities on Alliant Energy’s balance sheet in the third quarter of 2023. Based on the remeasurement of Alliant Energy parent company’s deferred tax assets in the third quarter of 2022 for the Iowa corporate income tax rate of 8.4% effective January 1, 2023, a charge of $8 million was recorded to income tax expense in Alliant Energy’s income statement in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.

NOTE 10. BENEFIT PLANS

NOTE 10(a) Pension and OPEB Plans -

Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

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NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

As of September 30, 2023, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $11 million, $6 million and $5 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years.

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

As of September 30, 2023, 274,960 shares were included in the calculation of diluted EPS related to the nonvested equity awards.

NOTE 11. DERIVATIVE INSTRUMENTS

Commodity Derivatives -

Notional Amounts - As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

During the nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of natural gas, FTR and electricity contracts and lower natural gas prices, partially offset by new FTRs resulting from the annual FTR auction in the second quarter of 2023 operated by MISO. Alliant Energy’s and IPL’s derivative liabilities decreased primarily due to settlement of natural gas contracts. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2023 and December 31, 2022, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that

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would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.

Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

Interest Rate Derivative - In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk. Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings. The related interest rate derivative was valued based on quoted prices that utilize current market interest rate forecasts. As of September 30, 2023, $6 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheet. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income/loss. As of September 30, 2023, accumulated other comprehensive income included $4 million of income related to the interest rate swap. For the three and nine months ended September 30, 2023, $1 million and $2 million, respectively, of reductions to interest expense were recorded in Alliant Energy’s income statement related to the interest rate swap.

NOTE 12. FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

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IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

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IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

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NOTE 13. COMMITMENTS AND CONTINGENCIES

NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of solar generation. At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $221 million, $175 million and $46 million, respectively.

NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

NOTE 13(c) Guarantees and Indemnifications -

Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations.

As of September 30, 2023, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2023 and December 31, 2022, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees.

Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees.

Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $51 million as of September 30, 2023 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2023 and December 31, 2022.

NOTE 13(d) Environmental Matters -

Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

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	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.

Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Cross-State Air Pollution Rule, Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act.

NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with the Federal Energy Regulatory Commission (FERC) requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.

NOTE 14. SEGMENTS OF BUSINESS

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

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Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

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NOTE 15. RELATED PARTIES

Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC billings to WPL	$41	$38	$119	$107
WPL billings to ATC	5	6	16	14

WPL owed ATC net amounts of $9 million as of September 30, 2023 and $10 million as of December 31, 2022.

ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

This MDA includes information relating to Alliant Energy, and IPL and WPL (collectively, the Utilities), as well as ATC Holdings, AEF and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such. The following discussion and analysis should be read in conjunction with the Financial Statements and the Notes included in this report, as well as the financial statements, notes and MDA included in the 2022 Form 10-K. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share.

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2023 HIGHLIGHTS

Key highlights since the filing of the 2022 Form 10-K include the following:

Customer Investments:

•In 2021, IPL filed for advance rate-making principles with the IUB for up to 400 MW of solar generation and 75 MW of battery storage. In April 2023, the IUB approved advance rate-making principles for up to 200 MW of solar generation. The IUB’s order included a cost target of $1,575/kilowatt, including AFUDC and transmission upgrade costs among other costs. In May 2023, IPL requested reconsideration of certain ratemaking principles for the up to 200 MW of solar generation, including the cost target and return on common equity. In June 2023, IPL and the IUB filed a joint motion for remand of the other 200 MW of solar generation and 75 MW of battery storage for further reconsideration by the IUB, which was granted by the court. In June 2023, the IUB granted reconsideration of advance rate-making principles for the 400 MW of solar generation and 75 MW of battery storage. In October 2023, the IUB issued an order approving a modified non-unanimous settlement agreement with the Iowa Office of Consumer Advocate among other stakeholders, for up to 400 MW of solar generation, subject to a cost target of $1,650/kilowatt, including AFUDC and transmission upgrade costs among other costs, and a related return on common equity of no less than 10.25% with the opportunity to request a higher return on common equity in future IPL retail electric rate review filings. Any reasonable and prudent costs incurred in excess of the cost target are eligible for recovery at the return on common equity determined in IPL retail electric rate review filings. The IUB’s order also included a consumer protection plan, which monitors IPL’s achievement of certain aggregate summer capacity factors for the up to 400 MW of solar generation projects during June, July and August each calendar year over 30 years. Actual three-year rolling average summer capacity factors will be compared to target capacity factors, which may result in surpluses or deficits that would be offset against one another and contribute to an accumulated balance in a given calendar year. Surpluses or deficits will be capped at $3 million in aggregate per year. At the end of the program, any accumulated deficit balance would be addressed in IPL’s next rate review, and any accumulated surplus balance would not result in any return to IPL. In November 2023, IPL accepted these advance rate-making principles.

•In October 2023, WPL received an oral decision from the PSCW authorizing WPL to construct, own and operate approximately 99 MW of battery storage at the Edgewater Generating Station.

•In August 2023, WPL received an order from the PSCW authorizing WPL to construct, own and operate 175 MW of battery storage, with 100 MW and 75 MW at the Grant County and Wood County solar projects, respectively.

•In June 2023, WPL filed requests with the PSCW for approval to construct improvements at the natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, which would increase the capacity and efficiency of the EGUs. A decision from the PSCW is currently expected by the second quarter of 2024.

•In April 2023, the IUB issued a certificate of public convenience, use and necessity (GCU Certificate) granting IPL approval to construct, own and operate up to 150 MW of solar generation and up to 75 MW of battery storage at the Wever project in Lee County, Iowa. In March 2023, the IUB issued a GCU Certificate granting IPL approval to construct, own and operate up to 50 MW of solar generation and up to 25 MW of battery storage at the Creston project in Union County, Iowa. These solar projects are included in the IUB’s October 2023 order approving advance rate-making principles for up to 400 MW of solar generation.

Rate Matters:

•In April 2023, WPL filed a retail electric and gas rate review with the PSCW for the 2024/2025 forward-looking Test Period. The key drivers for the filing include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and battery storage. The filing requested approval for WPL to implement increases in annual rates for its retail electric and gas customers of $111 million and $17 million in 2024, respectively, with any granted rate changes expected to be effective on January 1, 2024. WPL’s filing also requested approval to implement an additional $71 million increase in annual rates for its retail electric customers in 2025, with any granted rate changes expected to be effective on January 1, 2025. WPL also requested to maintain its current authorized return on common equity of 10% and implement an approximate 56% common equity component of its regulatory capital structure, as well as receive continued recovery of and a return on the remaining net book value of Edgewater Unit 5, which is currently expected to be retired by June 1, 2025. A decision from the PSCW is currently expected by the end of 2023.

•In October 2023, IPL filed a retail electric and gas rate review with the IUB for the October 2024 through September 2025 forward-looking Test Period. The key drivers for the filing include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and repowering of the existing Franklin County wind farm. The filing requested approval for IPL to implement increases in annual rates for its retail electric and gas customers of $160 million and $14 million, respectively, with any granted rate changes expected to be effective on October 1, 2024. IPL’s filing also requested approval to implement an additional $124 million increase in annual rates for its retail electric customers in 2025, with any granted rate changes expected to be effective on October 1, 2025. IPL also requested a return on common equity of 10% and a 52% common equity component of its regulatory capital structure, as well as to receive continued recovery of and a return on the remaining net book value of the Lansing Generating Station through 2037, which was retired in May 2023. A decision from the IUB is currently expected by the third quarter of 2024.

•In August 2023, the PSCW authorized WPL to collect $117 million in higher rates, plus interest, from its retail electric customers from October 2023 through December 2025 for fuel-related costs incurred by WPL in 2022 that were higher than fuel-related costs used to determine rates for such period.

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Legislative Matters:

•Refer to Note 9 for discussion of the Iowa corporate income tax rate that will be effective January 1, 2024, pursuant to Iowa tax reform enacted in 2022.

Financings and Common Stock Dividends:

•Refer to “Results of Operations” for discussion of expected future issuances of common stock and common stock dividends, and expected future issuances and retirements of long-term debt, by the end of 2024.

RESULTS OF OPERATIONS

Results of operations include financial information prepared in accordance with GAAP as well as utility electric margins and utility gas margins, which are not measures of financial performance under GAAP. Utility electric margins are defined as electric revenues less electric production fuel, purchased power and electric transmission service expenses. Utility gas margins are defined as gas revenues less cost of gas sold. Utility electric margins and utility gas margins are non-GAAP financial measures because they exclude other utility and non-utility revenues, other operation and maintenance expenses, depreciation and amortization expenses, and taxes other than income tax expense.

Management believes that utility electric and gas margins provide a meaningful basis for evaluating and managing utility operations since electric production fuel, purchased power and electric transmission service expenses and cost of gas sold are generally passed through to customers, and therefore, result in changes to electric and gas revenues that are comparable to changes in such expenses. The presentation of utility electric and gas margins herein is intended to provide supplemental information for investors regarding operating performance. These utility electric and gas margins may not be comparable to how other entities define utility electric and gas margin. Furthermore, these measures are not intended to replace operating income as determined in accordance with GAAP as an indicator of operating performance.

Additionally, the table below includes EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures. Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of segment performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance.

Financial Results Overview - Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners for the three months ended September 30 were as follows (dollars in millions, except per share amounts):

	2023		2022
	Income (Loss)	EPS	Income (Loss)	EPS
Utilities and Corporate Services	$281	$1.11	$249	$0.99
ATC Holdings	9	0.03	5	0.02
Non-utility and Parent	(31)	(0.12)	(27)	(0.11)
Alliant Energy Consolidated	$259	$1.02	$227	$0.90

Alliant Energy’s Utilities and Corporate Services net income increased by $32 million for the three-month period, primarily due to higher revenue requirements and AFUDC from WPL’s capital investments, and lower other operation and maintenance expenses. These items were partially offset by higher interest expense.

Alliant Energy’s Non-utility and Parent net income decreased by $4 million for the three-month period, primarily due to higher interest expense.

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For the three and nine months ended September 30, operating income and a reconciliation of utility electric and gas margins to the most directly comparable GAAP measure, operating income, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months	2023	2022	2023	2022	2023	2022
Operating income	$322	$309	$173	$171	$142	$131
Electric utility revenues	$995	$1,039	$551	$596	$444	$443
Electric production fuel and purchased power expenses	(231)	(274)	(99)	(140)	(132)	(134)
Electric transmission service expense	(154)	(157)	(115)	(115)	(39)	(42)
Utility Electric Margin (non-GAAP)	610	608	337	341	273	267
Gas utility revenues	47	62	31	33	16	29
Cost of gas sold expense	(12)	(26)	(12)	(14)	—	(13)
Utility Gas Margin (non-GAAP)	35	36	19	19	16	16
Other utility revenues	13	11	12	11	1	—
Non-utility revenues	22	23	—	—	—	—
Other operation and maintenance expenses	(160)	(172)	(84)	(90)	(64)	(70)
Depreciation and amortization expenses	(170)	(169)	(97)	(95)	(71)	(71)
Taxes other than income taxes expense	(28)	(28)	(14)	(15)	(13)	(11)
Operating income	$322	$309	$173	$171	$142	$131

	Alliant Energy		IPL		WPL
Nine Months	2023	2022	2023	2022	2023	2022
Operating income	$760	$769	$379	$389	$363	$357
Electric utility revenues	$2,562	$2,624	$1,370	$1,438	$1,192	$1,186
Electric production fuel and purchased power expenses	(553)	(633)	(213)	(290)	(341)	(343)
Electric transmission service expense	(438)	(428)	(316)	(303)	(122)	(125)
Utility Electric Margin (non-GAAP)	1,571	1,563	841	845	729	718
Gas utility revenues	400	418	224	224	176	194
Cost of gas sold expense	(226)	(242)	(127)	(126)	(99)	(117)
Utility Gas Margin (non-GAAP)	174	176	97	98	77	77
Other utility revenues	38	35	36	34	2	1
Non-utility revenues	66	70	—	—	—	—
Other operation and maintenance expenses	(499)	(492)	(264)	(260)	(197)	(193)
Depreciation and amortization expenses	(503)	(501)	(288)	(285)	(208)	(211)
Taxes other than income taxes expense	(87)	(82)	(43)	(43)	(40)	(35)
Operating income	$760	$769	$379	$389	$363	$357

Operating Income Variances - Variances between periods in operating income for the three and nine months ended September 30, 2023 compared to the same periods in 2022 were as follows (in millions):

	Three Months			Nine Months
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Total higher (lower) utility electric margin variance (Refer to details below)	$2	($4)	$6	$8	($4)	$11
Total lower utility gas margin variance (Refer to details below)	(1)	—	—	(2)	(1)	—
Total (higher) lower other operation and maintenance expenses variance (Refer to details below)	12	6	6	(7)	(4)	(4)
Total (higher) lower depreciation and amortization expenses (Refer to Note 2 for discussion of reductions to WPL's depreciation and amortization expense, which was partially offset by WPL's solar generation placed in service in 2022)	(1)	(2)	—	(2)	(3)	3
Other	1	2	(1)	(6)	2	(4)
	$13	$2	$11	($9)	($10)	$6

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Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), for the three and nine months ended September 30 were as follows:

Alliant Energy	Electric				Gas
	Revenues		MWhs Sold		Revenues		Dths Sold
	2023	2022	2023	2022	2023	2022	2023	2022
Three Months
Retail	$895	$908	6,821	6,788	$37	$50	3,283	3,584
Sales for resale:
Wholesale	59	68	795	774	N/A	N/A	N/A	N/A
Bulk power and other	25	47	1,409	985	N/A	N/A	N/A	N/A
Transportation/Other	16	16	14	16	10	12	29,776	30,982
	$995	$1,039	9,039	8,563	$47	$62	33,059	34,566
Nine Months
Retail	$2,310	$2,327	19,005	19,304	$367	$379	31,897	37,284
Sales for resale:
Wholesale	154	168	2,172	2,172	N/A	N/A	N/A	N/A
Bulk power and other	62	83	3,756	2,989	N/A	N/A	N/A	N/A
Transportation/Other	36	46	43	46	33	39	88,167	83,241
	$2,562	$2,624	24,976	24,511	$400	$418	120,064	120,525

IPL	Electric				Gas
	Revenues		MWhs Sold		Revenues		Dths Sold
	2023	2022	2023	2022	2023	2022	2023	2022
Three Months
Retail	$520	$559	3,736	3,736	$25	$25	1,658	1,739
Sales for resale:
Wholesale	21	19	213	208	N/A	N/A	N/A	N/A
Bulk power and other	3	9	332	373	N/A	N/A	N/A	N/A
Transportation/Other	7	9	8	9	6	8	9,999	9,743
	$551	$596	4,289	4,326	$31	$33	11,657	11,482
Nine Months
Retail	$1,291	$1,358	10,599	10,821	$204	$199	16,065	19,118
Sales for resale:
Wholesale	47	49	578	581	N/A	N/A	N/A	N/A
Bulk power and other	12	4	1,188	1,019	N/A	N/A	N/A	N/A
Transportation/Other	20	27	24	25	20	25	31,588	31,917
	$1,370	$1,438	12,389	12,446	$224	$224	47,653	51,035

WPL	Electric				Gas
	Revenues		MWhs Sold		Revenues		Dths Sold
	2023	2022	2023	2022	2023	2022	2023	2022
Three Months
Retail	$375	$349	3,085	3,052	$12	$25	1,625	1,845
Sales for resale:
Wholesale	38	49	582	566	N/A	N/A	N/A	N/A
Bulk power and other	22	38	1,077	612	N/A	N/A	N/A	N/A
Transportation/Other	9	7	6	7	4	4	19,777	21,239
	$444	$443	4,750	4,237	$16	$29	21,402	23,084
Nine Months
Retail	$1,019	$969	8,406	8,483	$163	$180	15,832	18,166
Sales for resale:
Wholesale	107	119	1,594	1,591	N/A	N/A	N/A	N/A
Bulk power and other	50	79	2,568	1,970	N/A	N/A	N/A	N/A
Transportation/Other	16	19	19	21	13	14	56,579	51,324
	$1,192	$1,186	12,587	12,065	$176	$194	72,411	69,490

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Sales Trends and Temperatures - Alliant Energy’s retail electric and gas sales volumes increased 1% and decreased 8%, respectively, for the three months ended September 30, 2023 compared to the same period in 2022, primarily due to changes in temperatures. Alliant Energy’s retail electric and gas sales volumes decreased 2% and 14%, respectively, for the nine months ended September 30, 2023 compared to the same period in 2022, primarily due to changes in temperatures.

Estimated increases (decreases) to electric and gas margins from the impacts of temperatures for the three and nine months ended September 30 were as follows (in millions):

	Electric Margins						Gas Margins
	Three Months			Nine Months			Three Months			Nine Months
	2023	2022	Change	2023	2022	Change	2023	2022	Change	2023	2022	Change
IPL	$7	$4	$3	$3	$15	($12)	($1)	$—	($1)	($4)	$4	($8)
WPL	3	—	3	(2)	10	(12)	—	—	—	(4)	2	(6)
Total Alliant Energy	$10	$4	$6	$1	$25	($24)	($1)	$—	($1)	($8)	$6	($14)

Electric Sales for Resale - Electric sales for resale volume changes were largely due to changes in sales in the wholesale energy markets operated by MISO. These changes are impacted by several factors, including the availability and dispatch of Alliant Energy’s EGUs and electricity demand within these wholesale energy markets. Changes in sales for resale revenues were largely offset by changes in fuel-related costs, and therefore, did not have a significant impact on electric margins.

Gas Transportation/Other - Gas transportation/other sales volume changes were largely due to changes in the gas volumes supplied to Alliant Energy’s natural gas-fired EGUs caused by the availability and dispatch of such EGUs. Changes in these transportation/other revenues did not have a significant impact on gas margins.

Utility Electric Margin Variances - The following items contributed to increased (decreased) utility electric margins for the three and nine months ended September 30, 2023 compared to the same periods in 2022 as follows (in millions):

	Three Months			Nine Months
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Lower (higher) WPL electric fuel-related costs, net of recoveries	($1)	$—	($1)	$12	$—	$12
Higher (lower) revenues at IPL due to changes in the renewable energy rider (mostly offset by changes in income taxes)	(3)	(3)	—	9	9	—
Estimated changes in sales volumes caused by temperatures	6	3	3	(24)	(12)	(12)
Other	—	(4)	4	11	(1)	11
	$2	($4)	$6	$8	($4)	$11

Utility Gas Margin Variances - The following items contributed to increased (decreased) utility gas margins for the three and nine months ended September 30, 2023 compared to the same periods in 2022 as follows (in millions):

	Three Months			Nine Months
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Estimated changes in sales volumes caused by temperatures	($1)	($1)	$—	($14)	($8)	($6)
Higher revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense)	—	—	—	7	7	—
Higher revenue requirements at WPL (a)	1	—	1	6	—	6
Other	(1)	1	(1)	(1)	—	—
	($1)	$—	$—	($2)	($1)	$—

(a)In December 2022, the PSCW issued an order authorizing an annual base rate increase of $9 million for WPL’s retail gas customers, covering the 2023 forward-looking Test Period, which reflects changes in weighted average cost of capital, updated depreciation rates and modifications to certain regulatory asset and regulatory liability amortizations. These retail gas rate changes were effective on January 1, 2023 and extend through the end of 2023.

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Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for the three and nine months ended September 30, 2023 compared to the same periods in 2022 as follows (in millions):

	Three Months			Nine Months
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Higher energy efficiency expense at IPL (mostly offset by higher revenues)	($1)	($1)	$—	($10)	($10)	$—
Lower (higher) generation and energy delivery expenses	3	1	2	(8)	—	(8)
Other	10	6	4	11	6	4
	$12	$6	$6	($7)	($4)	($4)

Other Income and Deductions Variances - The following items contributed to (increased) decreased other income and deductions for the three and nine months ended September 30, 2023 compared to the same periods in 2022 as follows (in millions):

	Three Months			Nine Months
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Higher interest expense primarily due to financings completed in 2023 and 2022, and higher interest rates	($16)	($1)	($7)	($54)	($2)	($24)
Higher AFUDC primarily due to changes in construction work in progress balances related to WPL’s solar generation	18	3	15	37	5	32
Other	8	(3)	2	6	(5)	3
	$10	($1)	$10	($11)	($2)	$11

Income Taxes - Refer to Note 9 for details of effective income tax rates.

Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations:

•    Financing Plans - Alliant Energy currently expects to issue up to $225 million of common stock in 2024 through one or more offerings and its Shareowner Direct Plan. The amount of common stock issued in 2024 will largely be used to fund capital contributions from Alliant Energy to WPL, which is dependent on the PSCW's decision on WPL's common equity component of its capital structure for the 2024/2025 forward-looking Test Period. IPL and AEF currently expect to issue up to $700 million and $1.0 billion of long-term debt, respectively, by the end of 2024. IPL and AEF have $500 million and $400 million of long-term debt, respectively, and AEF has $50 million of short-term borrowings, maturing in 2024.

•    Common Stock Dividends - Alliant Energy announced a 6% increase in its expected targeted 2024 annual common stock dividend to $1.92 per share, which is equivalent to a quarterly rate of $0.48 per share, beginning with the February 2024 dividend payment. The timing and amount of future dividends is subject to approved quarterly dividend declarations from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.

•    Cash Flows From Operating Activities - Alliant Energy, IPL and WPL currently expect an increase in future cash flows from operating activities resulting from the transfer of future renewable tax credits to other corporate taxpayers pursuant to the Inflation Reduction Act of 2022.

•    Higher Earnings on Increasing Rate Base - Alliant Energy, IPL and WPL currently expect an increase in earnings in 2024 compared to 2023 due to impacts from increasing revenue requirements related to investments in the utility business.

•    Depreciation and Amortization Expense - Alliant Energy, IPL and WPL currently expect an increase in depreciation and amortization expense in 2024 compared to 2023 due to capital projects placed in service in 2023 and 2024 and lower amortization of WPL’s West Riverside liquidated damages. Refer to Note 2 for discussion of WPL’s West Riverside liquidated damages.

•    Interest Expense - Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2024 compared to 2023 due to financings completed in 2023 and planned by the end of 2024 as discussed above, as well as expected higher interest rates.

•    AFUDC - Alliant Energy and WPL currently expect a decrease and IPL currently expects an increase in AFUDC in 2024 compared to 2023 largely due to changes in construction work in progress balances related to construction activity on capital projects.

LIQUIDITY AND CAPITAL RESOURCES

The liquidity and capital resources summary included in the 2022 Form 10-K has not changed materially, except as described below.

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Liquidity Position - At September 30, 2023, Alliant Energy had $206 million of cash and cash equivalents, $549 million ($119 million at the parent company, $250 million at IPL and $180 million at WPL) of available capacity under the single revolving credit facility and $109 million of available capacity at IPL under its sales of accounts receivable program.

Capital Structure - Capital structures at September 30, 2023 were as follows (Long-term Debt (including current maturities) (LD); Short-term Debt (SD); Common Equity (CE)):

Cash Flows - Selected information from the cash flows statements was as follows (in millions):

	Alliant Energy		IPL		WPL
	2023	2022	2023	2022	2023	2022
Cash, cash equivalents and restricted cash, January 1	$24	$40	$15	$34	$5	$2
Cash flows from (used for):
Operating activities	622	485	191	166	437	279
Investing activities	(952)	(599)	(177)	84	(680)	(612)
Financing activities	515	421	159	(239)	254	630
Net increase	185	307	173	11	11	297
Cash, cash equivalents and restricted cash, September 30	$209	$347	$188	$45	$16	$299

Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for the nine months ended September 30, 2023 compared to the same period in 2022 (in millions):

	Alliant Energy	IPL	WPL
Timing of WPL’s fuel-related cost recoveries from retail electric customers	$137	$—	$137
Changes in levels of gas stored underground and prepaid gas costs	97	46	51
Changes in the sales of accounts receivable at IPL	36	36	—
Changes in interest payments	(60)	4	(28)
Decreased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales	(38)	(20)	(18)
Other (primarily due to other changes in working capital)	(35)	(41)	16
	$137	$25	$158

Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for the nine months ended September 30, 2023 compared to the same period in 2022 (in millions):

	Alliant Energy	IPL	WPL
Higher utility construction and acquisition expenditures (a)	($328)	($158)	($170)
Changes in the amount of cash receipts on sold receivables	(52)	(52)	—
Higher non-utility construction and acquisition expenditures	(23)	—	—
Proceeds from sales of partial ownership interest in West Riverside in 2023	120	—	120
Other	(70)	(51)	(18)
	($353)	($261)	($68)

(a)Largely due to higher expenditures for IPL and WPL’s solar generation.

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Construction and Acquisition Expenditures - Construction and acquisition expenditures and financing plans are reviewed, approved and updated as part of the strategic planning process. Changes may result from a number of reasons, including regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems. Construction and acquisition expenditures for 2023 through 2027 are currently anticipated as follows (in millions), which are focused on the transition to cleaner energy and strengthening the resiliency and reliability of IPL’s and WPL’s electric grid, and include renewables and battery storage projects, dispatchable gas generation projects and wind repowering projects. Cost estimates represent Alliant Energy’s, IPL’s and WPL’s portion of construction expenditures and exclude AFUDC and capitalized interest, if applicable.

	Alliant Energy					IPL					WPL
	2023	2024	2025	2026	2027	2023	2024	2025	2026	2027	2023	2024	2025	2026	2027
Generation:
Renewables and battery storage projects	$790	$1,140	$665	$780	$775	$350	$575	$275	$445	$205	$440	$565	$390	$335	$570
Gas projects	40	120	325	610	500	10	55	135	310	125	30	15	125	295	375
Other	95	100	80	50	40	55	55	40	20	15	40	45	40	30	25
Distribution:
Electric systems	565	610	620	670	685	305	355	365	380	395	260	255	255	290	290
Gas systems	80	85	85	85	85	35	40	40	40	40	45	45	45	45	45
Other	220	220	205	240	280	50	45	50	50	45	35	40	30	25	30
	$1,790	$2,275	$1,980	$2,435	$2,365	$805	$1,125	$905	$1,245	$825	$850	$965	$885	$1,020	$1,335

Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for the nine months ended September 30, 2023 compared to the same period in 2022 (in millions):

	Alliant Energy	IPL	WPL
Higher net proceeds from common stock issuances	$182	$—	$—
Distributions to noncontrolling interest in 2022	29	—	29
Higher (lower) capital contributions from IPL’s and WPL’s parent company, Alliant Energy	—	60	(175)
Higher (lower) net proceeds from issuance of long-term debt	(80)	296	(291)
Capital contributions from noncontrolling interest in 2022	(29)	—	(29)
Higher payments to retire long-term debt	(25)	—	—
(Higher) lower common stock dividends	(19)	30	(5)
Net changes in the amount of commercial paper and other short-term borrowings outstanding	(9)	—	66
Other	45	12	29
	$94	$398	($376)

State Regulatory Financing Authorization - In March 2023, WPL received authorization from the PSCW to have up to $500 million of short-term borrowings and/or letters of credit outstanding at any time through the expiration date of WPL’s credit facility agreement.

Common Stock Issuances and Common Stock Dividends - Refer to Note 6 for discussion of common stock issuances by Alliant Energy in 2023. Refer to “Results of Operations” for discussion of expected issuances of common stock and common stock dividends in 2024.

Short-term Debt - Refer to Note 7(a) for discussion of Alliant Energy’s, IPL’s and WPL’s single credit facility agreement that was amended and extended in March 2023, which includes a revised cross-default provision related to prepayment of material debt prior to the stated maturity and certain other confirming changes, as well as details for proceeds from AEF’s December 2022 term loan credit agreement.

Long-term Debt - Refer to Note 7(b) for discussion of various issuances and retirements of long-term debt by Alliant Energy, AEF, IPL and WPL in 2023. Refer to “Results of Operations” for discussion of expected future issuances and retirements of long-term debt by the end of 2024.

Interest Rate Risk - As of September 30, 2023, Alliant Energy’s exposure to risk resulting from changes in interest rates associated with variable-rate borrowings was mitigated primarily due to its issuance of convertible senior notes and an interest rate swap on a portion of its variable-rate term loan borrowings, as well as WPL’s issuance of green bonds and IPL’s issuance of senior debentures, all of which were executed in 2023. Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at September 30, 2023, Alliant Energy’s annual pre-tax expense would increase by approximately $6 million.

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Off-Balance Sheet Arrangements and Certain Financial Commitments - A summary of Alliant Energy’s and IPL’s off-balance sheet arrangements and Alliant Energy’s, IPL’s and WPL’s contractual obligations is included in the 2022 Form 10-K and has not changed materially from the items reported in the 2022 Form 10-K, except for the items described in Notes 4, 7 and 13.

OTHER MATTERS

Critical Accounting Policies and Estimates - The summary of critical accounting policies and estimates included in the 2022 Form 10-K has not changed materially, except as described below.

Long-Lived Assets -

Regulated Operations -

Generating Units Subject to Early Retirement - In May 2023, IPL retired the Lansing Generating Station. IPL is currently allowed a full recovery of and a full return on this EGU from both its retail and wholesale customers, and as a result, Alliant Energy and IPL concluded that no impairment was required as of September 30, 2023. Refer to Note 2 for further discussion of the Lansing retirement.

IPL’s Solar Generation Projects Under Construction - As discussed in “2023 Highlights,” IPL accepted the IUB’s advance rate-making principles approved in October 2023 for 400 MW of solar generation. Alliant Energy and IPL review property, plant and equipment for possible impairment whenever events or changes in circumstances indicate all or a portion of the carrying value of the assets may be disallowed for rate-making purposes. If IPL is disallowed recovery of any portion of, or is only allowed a partial return on, the carrying value of the solar generation projects under construction, then an impairment charge is recognized. IPL currently expects estimated construction costs associated with the 400 MW of new solar generation will exceed the cost target approved by the IUB by approximately 10%. Alliant Energy and IPL concluded that there was not a probable disallowance of anticipated higher rate base amounts as of September 30, 2023 given construction costs were reasonably and prudently incurred.

Environmental Matters - The summary of environmental matters included in the 2022 Form 10-K has not changed materially, except as described below.

Environmental Regulation -

Clean Air Act (CAA) Section 111(d) - In May 2023, the EPA published proposed standards under Section 111(d) of the CAA, which establish emission guidelines for states to implement Best System of Emission Reduction standards for greenhouse gases emissions from existing fossil-fueled EGUs and certain combustion turbines, and would be phased in beginning in 2030. The EPA also proposed to repeal the Affordable Clean Energy rule. The EPA’s proposed standards would require states to implement plans to reduce carbon dioxide emissions from existing fossil-fueled EGUs and certain combustion turbines through various measures, including retirement, enforceable limits on operational capacity, co-firing with low-greenhouse gases fuels, or other technological controls. State plans must be submitted within 24 months of the final rule’s effective date and are subject to EPA approval. The proposed standards could impact IPL’s coal-fired Ottumwa Generating Station, George Neal Generating Station, Prairie Creek Generating Station Unit 3 and Louisa Generating Station, and IPL’s natural gas-fired Burlington Generating Station and Prairie Creek Generating Station Unit 4. In addition, the proposed standards could impact natural gas-fired combustion turbines with a capacity of 300 MW or more, including IPL’s Marshalltown Generating Station and Emery Generating Station, and WPL’s Riverside Energy Center and West Riverside Energy Center. The proposed standards are currently not expected to impact WPL’s coal-fired Columbia Energy Center or Edgewater Generating Station given current plans to retire these EGUs prior to the proposed 2030 implementation deadline. The timeline for expected issuance of the EPA’s final reconsidered 111(d) rule cannot be predicted with certainty, but is expected to be issued in 2024. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters.

Clean Air Act Section 111(b) - In May 2023, the EPA published proposed standards under Section 111(b) of the CAA, which establish carbon dioxide emissions limits from certain new and reconstructed fossil-fueled EGUs and would apply prospectively. The timeline for expected issuance of the EPA’s final reconsidered 111(b) rule cannot be predicted with certainty, but is expected to be issued in 2024. Marshalltown and West Riverside are currently subject to the EPA’s Section 111(b) regulation. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these standards.

Coal Combustion Residuals (CCR) Rule - In May 2023, the EPA published proposed amendments to the CCR Rule, which regulates CCR as a non-hazardous waste. These proposed amendments would expand the scope of regulation to include coal ash ponds at sites that no longer produce electricity and inactive landfills, including some IPL and WPL facilities. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these updates.

Environmental Stewardship - Alliant Energy’s current voluntary environmental-related goals include the following:

•By 2030, reduce greenhouse gases emissions from its utility operations by 50% from 2005 levels, reduce its electric utility water supply by 75% from 2005 levels and electrify 100% of its owned light-duty fleet vehicles.

•By 2040, eliminate all coal-fired EGUs from its generating fleet and reduce greenhouse gases emissions from its utility operations by 80% from 2005 levels.

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•By 2050, aspire to achieve net-zero greenhouse gases emissions from its utility operations.

Alliant Energy’s aspirational greenhouse gases goal includes EPA reportable emissions based on applicable regulatory compliance requirements for carbon dioxide, methane and nitrous oxide from its owned fossil-fueled EGUs and distribution of natural gas. In addition, Alliant Energy’s environmental stewardship efforts include a goal to partner to plant more than 1 million trees by the end of 2030. Future updates to sustainable energy plans and attaining these goals will depend on future economic developments, evolving energy technologies and emerging trends in Alliant Energy’s service territories.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Quantitative and Qualitative Disclosures About Market Risk are reported in the 2022 Form 10-K and have not changed materially.

ITEM 4. CONTROLS AND PROCEDURES

Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s Chief Executive Officer, Chief Financial Officer and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures (as defined in Rule 13a-15(e) of the Securities Exchange Act of 1934, as amended) as of September 30, 2023 pursuant to the requirements of the Securities Exchange Act of 1934, as amended. Based on their evaluation, the Chief Executive Officers and the Chief Financial Officer concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the quarter ended September 30, 2023.

There was no change in Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting that occurred during the quarter ended September 30, 2023 that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s, IPL’s or WPL’s internal control over financial reporting.

PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

None. SEC regulations require Alliant Energy, IPL and WPL to disclose information about certain proceedings arising under federal, state or local environmental provisions when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions that Alliant Energy, IPL and WPL reasonably believe will exceed a specified threshold. Pursuant to the SEC regulations, Alliant Energy, IPL and WPL use a threshold of $1 million for purposes of determining whether disclosure of any such proceedings is required. Applying this threshold, there are no environmental matters to disclose for this period.

ITEM 1A. RISK FACTORS

The risk factors described in Item 1A in the 2022 Form 10-K have not changed materially.

ITEM 2. UNREGISTERED SALES OF EQUITY SECURITIES, USE OF PROCEEDS AND ISSUER PURCHASES OF EQUITY SECURITIES

A summary of Alliant Energy common stock repurchases for the quarter ended September 30, 2023 was as follows:

	Total Number	Average Price	Total Number of Shares	Maximum Number (or Approximate
	of Shares	Paid Per	Purchased as Part of	Dollar Value) of Shares That May
Period	Purchased (a)	Share	Publicly Announced Plan	Yet Be Purchased Under the Plan (a)
July 1 through July 31	6,298	$52.95	—	N/A
August 1 through August 31	3,724	50.31	—	N/A
September 1 through September 30	38	49.97	—	N/A
	10,060	51.97	—

(a)All shares were purchased on the open market and held in a rabbi trust under the Alliant Energy Deferred Compensation Plan. There is no limit on the number of shares of Alliant Energy common stock that may be held under the Deferred Compensation Plan, which currently does not have an expiration date.

ITEM 5. OTHER INFORMATION

(c)During the quarter ended September 30, 2023, no director or officer of Alliant Energy, IPL or WPL adopted or terminated a Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement, as each term is defined in Item 408(a) of Regulation S-K.

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ITEM 6. EXHIBITS

The following Exhibits are filed herewith or incorporated herein by reference.

Exhibit Number	Description
4.1	Officer’s Certificate, dated as of September 21, 2023, creating IPL’s 5.70% Senior Debentures due October 15, 2033 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed September 21, 2023 (File No. 1-4117))
31.1	Certification of the Chief Executive Officer for Alliant Energy
31.2	Certification of the Chief Financial Officer for Alliant Energy
31.3	Certification of the Chief Executive Officer for IPL
31.4	Certification of the Chief Financial Officer for IPL
31.5	Certification of the Chief Executive Officer for WPL
31.6	Certification of the Chief Financial Officer for WPL
32.1	Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for Alliant Energy
32.2	Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for IPL
32.3	Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for WPL
101.INS	Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH	Inline XBRL Taxonomy Extension Schema Document
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB	Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document
104	Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company have each duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized on the 3rd day of November 2023.

ALLIANT ENERGY CORPORATION
Registrant
By: /s/ Benjamin M. Bilitz	Chief Accounting Officer and Controller
Benjamin M. Bilitz	(Principal Accounting Officer and Authorized Signatory)

INTERSTATE POWER AND LIGHT COMPANY
Registrant
By: /s/ Benjamin M. Bilitz	Chief Accounting Officer and Controller
Benjamin M. Bilitz	(Principal Accounting Officer and Authorized Signatory)

WISCONSIN POWER AND LIGHT COMPANY
Registrant
By: /s/ Benjamin M. Bilitz	Chief Accounting Officer and Controller
Benjamin M. Bilitz	(Principal Accounting Officer and Authorized Signatory)

38

EX-31.1

Exhibit 31.1

Certification of the Chief Executive Officer for Alliant Energy Corporation

I, John O. Larsen, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Alliant Energy Corporation;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ John O. Larsen

John O. Larsen

Chair and Chief Executive Officer

EX-31.2

Exhibit 31.2

Certification of the Chief Financial Officer for Alliant Energy Corporation

I, Robert J. Durian, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Alliant Energy Corporation;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ Robert J. Durian

Robert J. Durian

Executive Vice President and Chief Financial Officer

EX-31.3

Exhibit 31.3

Certification of the Chief Executive Officer for Interstate Power and Light Company

I, Lisa M. Barton, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Interstate Power and Light Company;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ Lisa M. Barton

Lisa M. Barton

Chief Executive Officer

EX-31.4

Exhibit 31.4

Certification of the Chief Financial Officer for Interstate Power and Light Company

I, Robert J. Durian, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Interstate Power and Light Company;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ Robert J. Durian

Robert J. Durian

Executive Vice President and Chief Financial Officer

EX-31.5

Exhibit 31.5

Certification of the Chief Executive Officer for Wisconsin Power and Light Company

I, Lisa M. Barton, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Wisconsin Power and Light Company;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ Lisa M. Barton

Lisa M. Barton

Chief Executive Officer

EX-31.6

Exhibit 31.6

Certification of the Chief Financial Officer for Wisconsin Power and Light Company

I, Robert J. Durian, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Wisconsin Power and Light Company;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2023

/s/ Robert J. Durian

Robert J. Durian

Executive Vice President and Chief Financial Officer

EX-32.1

Exhibit 32.1

Written Statement of the Chief Executive Officer and Chief Financial Officer

Pursuant to 18 U.S.C. §1350

Solely for the purposes of complying with 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, we, the undersigned Chief Executive Officer and Chief Financial Officer of Alliant Energy Corporation (the “Company”), hereby certify, based on our knowledge, that the Quarterly Report on Form 10-Q of the Company for the quarter ended September 30, 2023 (the “Report”) fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934 and that information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ John O. Larsen

John O. Larsen

Chair and Chief Executive Officer

/s/ Robert J. Durian

Robert J. Durian

Executive Vice President and Chief Financial Officer

November 3, 2023

EX-32.2

Exhibit 32.2

Written Statement of the Chief Executive Officer and Chief Financial Officer

Pursuant to 18 U.S.C. §1350

Solely for the purposes of complying with 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, we, the undersigned Chief Executive Officer and Chief Financial Officer of Interstate Power and Light Company (the “Company”), hereby certify, based on our knowledge, that the Quarterly Report on Form 10-Q of the Company for the quarter ended September 30, 2023 (the “Report”) fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934 and that information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ Lisa M. Barton

Lisa M. Barton

Chief Executive Officer

/s/ Robert J. Durian

Robert J. Durian

Executive Vice President and Chief Financial Officer

November 3, 2023

EX-32.3

Exhibit 32.3

Written Statement of the Chief Executive Officer and Chief Financial Officer

Pursuant to 18 U.S.C. §1350

Solely for the purposes of complying with 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, we, the undersigned Chief Executive Officer and Chief Financial Officer of Wisconsin Power and Light Company (the “Company”), hereby certify, based on our knowledge, that the Quarterly Report on Form 10-Q of the Company for the quarter ended September 30, 2023 (the “Report”) fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934 and that information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ Lisa M. Barton

Lisa M. Barton

Chief Executive Officer

/s/ Robert J. Durian

Robert J. Durian

Executive Vice President and Chief Financial Officer

November 3, 2023

XML

Document And Entity Information	9 Months Ended
	Sep. 30, 2023 shares
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity Registrant Name	ALLIANT ENERGY CORP
Entity Central Index Key	0000352541
Entity Incorporation, State or Country Code	WI
Entity Address, Address Line One	4902 N. Biltmore Lane
Entity Address, City or Town	Madison
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	53718
City Area Code	608
Local Phone Number	458-3311
Entity File Number	1-9894
Entity Tax Identification Number	39-1380265
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	LNT
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	255,179,087
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
IPL [Member]
Entity Information [Line Items]
Entity Registrant Name	INTERSTATE POWER & LIGHT CO
Entity Central Index Key	0000052485
Entity Incorporation, State or Country Code	IA
Entity Address, Address Line One	Alliant Energy Tower
Entity Address, City or Town	Cedar Rapids
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	52401
City Area Code	319
Local Phone Number	786-4411
Entity File Number	1-4117
Entity Tax Identification Number	42-0331370
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	13,370,788
WPL [Member]
Entity Information [Line Items]
Entity Registrant Name	WISCONSIN POWER & LIGHT CO
Entity Central Index Key	0000107832
Entity Incorporation, State or Country Code	WI
Entity Address, Address Line One	4902 N. Biltmore Lane
Entity Address, City or Town	Madison
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	53718
City Area Code	608
Local Phone Number	458-3311
Entity File Number	0-337
Entity Tax Identification Number	39-0714890
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	13,236,601

XML

Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues:
Electric utility	$ 995	$ 1,039	$ 2,562	$ 2,624
Gas utility	47	62	400	418
Other utility	13	11	38	35
Non-utility	22	23	66	70
Total revenues	1,077	1,135	3,066	3,147
Operating expenses:
Electric production fuel and purchased power	231	274	553	633
Electric transmission service	154	157	438	428
Cost of gas sold	12	26	226	242
Other operation and maintenance	160	172	499	492
Depreciation and amortization	170	169	503	501
Taxes other than income taxes	28	28	87	82
Total operating expenses	755	826	2,306	2,378
Operating income	322	309	760	769
Other (income) and deductions:
Interest expense	99	83	289	235
Equity income from unconsolidated investments, net	(14)	(5)	(45)	(37)
Allowance for funds used during construction	(28)	(10)	(71)	(34)
Other	1	0	2	0
Total other (income) and deductions	58	68	175	164
Income before income taxes	264	241	585	605
Income tax expense (benefit)	5	14	3	26
Net income			582	579
Net income attributable to common shareowners	$ 259	$ 227	$ 582	$ 579
Weighted average number of common shares outstanding:
Basic (in shares)	253,500	251,000	252,100	250,800
Diluted (in shares)	253,800	251,300	252,400	251,100
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 1.02	$ 0.90	$ 2.31	$ 2.31
Diluted (in dollars per share)	$ 1.02	$ 0.90	$ 2.31	$ 2.31
IPL [Member]
Revenues:
Electric utility	$ 551	$ 596	$ 1,370	$ 1,438
Gas utility	31	33	224	224
Other utility	12	11	36	34
Total revenues	594	640	1,630	1,696
Operating expenses:
Electric production fuel and purchased power	99	140	213	290
Electric transmission service	115	115	316	303
Cost of gas sold	12	14	127	126
Other operation and maintenance	84	90	264	260
Depreciation and amortization	97	95	288	285
Taxes other than income taxes	14	15	43	43
Total operating expenses	421	469	1,251	1,307
Operating income	173	171	379	389
Other (income) and deductions:
Interest expense	38	37	113	111
Allowance for funds used during construction	(6)	(3)	(13)	(8)
Other	2	(1)	3	(2)
Total other (income) and deductions	34	33	103	101
Income before income taxes	139	138	276	288
Income tax expense (benefit)	(31)	(16)	(55)	(39)
Net income	170	154	331	327
WPL [Member]
Revenues:
Electric utility	444	443	1,192	1,186
Gas utility	16	29	176	194
Other utility	1	0	2	1
Total revenues	461	472	1,370	1,381
Operating expenses:
Electric production fuel and purchased power	132	134	341	343
Electric transmission service	39	42	122	125
Cost of gas sold	0	13	99	117
Other operation and maintenance	64	70	197	193
Depreciation and amortization	71	71	208	211
Taxes other than income taxes	13	11	40	35
Total operating expenses	319	341	1,007	1,024
Operating income	142	131	363	357
Other (income) and deductions:
Interest expense	38	31	110	86
Allowance for funds used during construction	(22)	(7)	(58)	(26)
Other	(2)	0	(3)	0
Total other (income) and deductions	14	24	49	60
Income before income taxes	128	107	314	297
Income tax expense (benefit)	21	16	47	50
Net income	$ 107	$ 91	$ 267	$ 247

XML

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 206	$ 20
Accounts receivable, less allowance for expected credit losses	486	516
Production fuel, at weighted average cost	44	53
Gas stored underground, at weighted average cost	87	132
Materials and supplies, at weighted average cost	196	140
Regulatory assets	179	166
Other	174	223
Total current assets	1,372	1,250
Property, plant and equipment, net	16,633	16,247
Investments:
ATC Holdings	380	358
Other	214	201
Total investments	594	559
Other assets:
Regulatory assets	2,090	1,880
Deferred charges and other	215	227
Total other assets	2,305	2,107
Total assets	20,904	20,163
Current liabilities:
Current maturities of long-term debt	409	408
Commercial paper	451	642
Other short-term borrowings	50	0
Accounts payable	604	756
Regulatory liabilities	92	206
Other	329	351
Total current liabilities	1,935	2,363
Long-term debt, net (excluding current portion)	8,429	7,668
Other liabilities:
Deferred tax liabilities	1,913	1,943
Regulatory liabilities	1,095	1,118
Pension and other benefit obligations	262	277
Other	544	518
Total other liabilities	3,814	3,856
Commitments and contingencies (Note 13)
Common equity:
Common stock	3	3
Additional paid-in capital	2,982	2,777
Retained earnings	3,750	3,509
Accumulated other comprehensive income	4	0
Shares in deferred compensation trust - 393,781 and 402,134 shares at a weighted average cost of $34.13 and $32.63 per share	(13)	(13)
Total common equity	6,726	6,276
Total liabilities and equity	20,904	20,163
IPL [Member]
Current assets:
Cash and cash equivalents	188	15
Accounts receivable, less allowance for expected credit losses	258	259
Production fuel, at weighted average cost	22	23
Gas stored underground, at weighted average cost	40	60
Materials and supplies, at weighted average cost	111	83
Regulatory assets	86	85
Other	70	93
Total current assets	775	618
Property, plant and equipment, net	8,042	8,046
Other assets:
Regulatory assets	1,504	1,301
Deferred charges and other	106	110
Total other assets	1,610	1,411
Total assets	10,427	10,075
Current liabilities:
Accounts payable	255	239
Accounts payable to associated companies	59	28
Accrued taxes	68	52
Accrued interest	41	35
Regulatory liabilities	63	114
Other	84	113
Total current liabilities	570	581
Long-term debt, net (excluding current portion)	3,944	3,646
Other liabilities:
Deferred tax liabilities	987	1,047
Regulatory liabilities	592	640
Pension and other benefit obligations	59	62
Other	286	291
Total other liabilities	1,924	2,040
Commitments and contingencies (Note 13)
Common equity:
Common stock	33	33
Additional paid-in capital	2,867	2,807
Retained earnings	1,089	968
Total common equity	3,989	3,808
Total liabilities and equity	10,427	10,075
WPL [Member]
Current assets:
Cash and cash equivalents	16	5
Accounts receivable, less allowance for expected credit losses	214	244
Production fuel, at weighted average cost	21	29
Gas stored underground, at weighted average cost	47	73
Materials and supplies, at weighted average cost	82	54
Regulatory assets	93	81
Prepaid gross receipts tax	36	42
Other	50	60
Total current assets	559	588
Property, plant and equipment, net	8,085	7,722
Other assets:
Regulatory assets	586	579
Deferred charges and other	71	98
Total other assets	657	677
Total assets	9,301	8,987
Current liabilities:
Commercial paper	120	290
Accounts payable	281	456
Regulatory liabilities	29	92
Other	117	111
Total current liabilities	547	949
Long-term debt, net (excluding current portion)	3,069	2,770
Other liabilities:
Deferred tax liabilities	796	789
Regulatory liabilities	503	478
Pension and other benefit obligations	128	140
Other	393	370
Total other liabilities	1,820	1,777
Commitments and contingencies (Note 13)
Common equity:
Common stock	66	66
Additional paid-in capital	2,478	2,233
Retained earnings	1,321	1,192
Total common equity	3,865	3,491
Total liabilities and equity	$ 9,301	$ 8,987

XML

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	480,000,000	480,000,000
Common stock, shares outstanding (in shares)	255,179,087	251,134,966
Shares in deferred compensation trust (in shares)	393,781	402,134
Shares in deferred compensation trust, weighted average cost per share (in dollars per share)	$ 34.13	$ 32.63
IPL [Member]
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	24,000,000	24,000,000
Common stock, shares outstanding (in shares)	13,370,788	13,370,788
WPL [Member]
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	18,000,000	18,000,000
Common stock, shares outstanding (in shares)	13,236,601	13,236,601

XML

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net income	$ 582	$ 579
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	503	501
Equity component of allowance for funds used during construction	(53)	(25)
Other	15	25
Other changes in assets and liabilities:
Accounts receivable	(279)	(425)
Materials and supplies	(56)	(13)
Derivative assets	102	(184)
Regulatory assets	40	(102)
Accounts payable	(91)	90
Derivative liabilities	(13)	89
Regulatory liabilities	(126)	89
Other	(2)	(139)
Net cash flows from operating activities	622	485
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(1,201)	(873)
Other construction and acquisition expenditures	(92)	(69)
Cash receipts on sold receivables	306	358
Proceeds from sales of partial ownership interest in West Riverside	120	0
Other	(85)	(15)
Net cash flows from (used for) investing activities	(952)	(599)
Cash flows from (used for) financing activities:
Common stock dividends	(341)	(322)
Proceeds from issuance of common stock, net	201	19
Proceeds from issuance of long-term debt	1,158	1,238
Payments to retire long-term debt	(404)	(379)
Net change in commercial paper and other short-term borrowings	(141)	(132)
Contributions from noncontrolling interest	0	29
Distributions to noncontrolling interest	0	(29)
Other	42	(3)
Net cash flows from (used for) financing activities	515	421
Net increase (decrease) in cash, cash equivalents and restricted cash	185	307
Cash, cash equivalents and restricted cash at beginning of period	24	40
Cash, cash equivalents and restricted cash at end of period	209	347
Supplemental cash flows information:
Interest	(280)	(220)
Income taxes, net	(6)	(7)
Significant non-cash investing and financing activities:
Accrued capital expenditures	287	403
Beneficial interest obtained in exchange for securitized accounts receivable	236	248
IPL [Member]
Cash flows from operating activities:
Net income	331	327
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	288	285
Deferred tax benefit and tax credits	(17)	(24)
Other	(6)	(8)
Other changes in assets and liabilities:
Accounts receivable	(306)	(397)
Derivative assets	53	(118)
Regulatory assets	55	18
Accounts payable	(45)	71
Derivative liabilities	(25)	62
Regulatory liabilities	(90)	61
Deferred income taxes	(44)	(30)
Other	(3)	(81)
Net cash flows from operating activities	191	166
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(427)	(269)
Cash receipts on sold receivables	306	358
Other	(56)	(5)
Net cash flows from (used for) investing activities	(177)	84
Cash flows from (used for) financing activities:
Common stock dividends	(210)	(240)
Capital contributions from parent	60	0
Proceeds from issuance of long-term debt	296	0
Other	13	1
Net cash flows from (used for) financing activities	159	(239)
Net increase (decrease) in cash, cash equivalents and restricted cash	173	11
Cash, cash equivalents and restricted cash at beginning of period	15	34
Cash, cash equivalents and restricted cash at end of period	188	45
Supplemental cash flows information:
Interest	(107)	(111)
Income taxes, net	36	33
Significant non-cash investing and financing activities:
Accrued capital expenditures	108	43
Beneficial interest obtained in exchange for securitized accounts receivable	236	248
WPL [Member]
Cash flows from operating activities:
Net income	267	247
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	208	211
Equity component of allowance for funds used during construction	(43)	(19)
Other	5	23
Other changes in assets and liabilities:
Derivative assets	55	(66)
Regulatory assets	(16)	(120)
Accounts payable	(55)	5
Regulatory liabilities	(37)	28
Other	53	(30)
Net cash flows from operating activities	437	279
Cash flows from (used for) investing activities:
Utility business construction and acquisition expenditures	(774)	(604)
Proceeds from sales of partial ownership interest in West Riverside	120	0
Other	(26)	(8)
Net cash flows from (used for) investing activities	(680)	(612)
Cash flows from (used for) financing activities:
Common stock dividends	(138)	(133)
Capital contributions from parent	245	420
Proceeds from issuance of long-term debt	297	588
Net change in commercial paper and other short-term borrowings	(170)	(236)
Contributions from noncontrolling interest	0	29
Distributions to noncontrolling interest	0	(29)
Other	20	(9)
Net cash flows from (used for) financing activities	254	630
Net increase (decrease) in cash, cash equivalents and restricted cash	11	297
Cash, cash equivalents and restricted cash at beginning of period	5	2
Cash, cash equivalents and restricted cash at end of period	16	299
Supplemental cash flows information:
Interest	(106)	(78)
Income taxes, net	(63)	(51)
Significant non-cash investing and financing activities:
Accrued capital expenditures	$ 172	$ 355

XML

Summary Of Significant Accounting Policies

9 Months Ended

Sep. 30, 2023

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.

In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

NOTE 1(b) Cash and Cash Equivalents - At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.

IPL [Member]

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.

In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

NOTE 1(b) Cash and Cash Equivalents - At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.

WPL [Member]

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.

In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

NOTE 1(b) Cash and Cash Equivalents - At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.

XML

Regulatory Matters

9 Months Ended

Sep. 30, 2023

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Tax-related - Refer to Note 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2023.

Assets retired early and Asset retirement obligations - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset (assets retired early) on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of September 30, 2023 was $221 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. In September 2023, the Federal Energy Regulatory Commission approved continued recovery of the remaining net book value of Lansing from IPL’s wholesale customers. IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period includes a request for continued recovery of the remaining net book value of Lansing through 2037. In addition, IPL reclassified the remaining net book value of the associated AROs from property, plant and equipment to a regulatory asset (AROs) on Alliant Energy’s and IPL’s balance sheets.

Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and nine months ended September 30, 2023.

IPL [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Tax-related - Refer to Note 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2023.

Assets retired early and Asset retirement obligations - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset (assets retired early) on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of September 30, 2023 was $221 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. In September 2023, the Federal Energy Regulatory Commission approved continued recovery of the remaining net book value of Lansing from IPL’s wholesale customers. IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period includes a request for continued recovery of the remaining net book value of Lansing through 2037. In addition, IPL reclassified the remaining net book value of the associated AROs from property, plant and equipment to a regulatory asset (AROs) on Alliant Energy’s and IPL’s balance sheets.

Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and nine months ended September 30, 2023.

WPL [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Tax-related - Refer to Note 9 for discussion of Iowa Tax Reform, which resulted in a decrease in Alliant Energy’s and IPL’s tax-related regulatory assets in the third quarter of 2023.

Assets retired early and Asset retirement obligations - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset (assets retired early) on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of September 30, 2023 was $221 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. In September 2023, the Federal Energy Regulatory Commission approved continued recovery of the remaining net book value of Lansing from IPL’s wholesale customers. IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period includes a request for continued recovery of the remaining net book value of Lansing through 2037. In addition, IPL reclassified the remaining net book value of the associated AROs from property, plant and equipment to a regulatory asset (AROs) on Alliant Energy’s and IPL’s balance sheets.

Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the nine months ended September 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and nine months ended September 30, 2023.

XML

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENTIn March 2023 and June 2023, Madison Gas and Electric Company and WEC Energy Group, Inc., respectively, acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interest in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements for the nine months ended September 30, 2023. As a result of these transactions, WPL’s undivided current ownership interest in West Riverside is 73.8%.
IPL [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENTIn March 2023 and June 2023, Madison Gas and Electric Company and WEC Energy Group, Inc., respectively, acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interest in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements for the nine months ended September 30, 2023. As a result of these transactions, WPL’s undivided current ownership interest in West Riverside is 73.8%.
WPL [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENTIn March 2023 and June 2023, Madison Gas and Electric Company and WEC Energy Group, Inc., respectively, acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interest in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements for the nine months ended September 30, 2023. As a result of these transactions, WPL’s undivided current ownership interest in West Riverside is 73.8%.

XML

Receivables

9 Months Ended

Sep. 30, 2023

Receivables [Line Items]

Receivables

RECEIVABLES

NOTE 4(a) - Accounts Receivable - For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

NOTE 4(b) - Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. In March 2023, IPL amended and extended through March 2024 the purchase commitment from the third party to which it sells its receivables. The limit on cash proceeds fluctuates between $5 million and $110 million, which IPL may change periodically throughout the year. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of September 30, 2023, IPL had $109 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Maximum outstanding aggregate cash proceeds	$94	$36	$110	$66
Average outstanding aggregate cash proceeds	46	3	68	8

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

	September 30, 2023	December 31, 2022
Customer accounts receivable	$161	$145
Unbilled utility revenues	88	132
Other receivables	1	—
Receivables sold to third party	250	277
Less: cash proceeds	1	80
Deferred proceeds	249	197
Less: allowance for expected credit losses	13	12
Fair value of deferred proceeds	$236	$185

As of September 30, 2023, outstanding receivables past due under the Receivables Agreement were $18 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Collections	$616	$670	$1,720	$1,731
Write-offs, net of recoveries	5	3	9	6

Effective October 2023, the limit on cash proceeds under the Receivables Agreement is $5 million.

IPL [Member]

Receivables [Line Items]

Receivables

RECEIVABLES

NOTE 4(a) - Accounts Receivable - For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

NOTE 4(b) - Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. In March 2023, IPL amended and extended through March 2024 the purchase commitment from the third party to which it sells its receivables. The limit on cash proceeds fluctuates between $5 million and $110 million, which IPL may change periodically throughout the year. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. As of September 30, 2023, IPL had $109 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Maximum outstanding aggregate cash proceeds	$94	$36	$110	$66
Average outstanding aggregate cash proceeds	46	3	68	8

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

	September 30, 2023	December 31, 2022
Customer accounts receivable	$161	$145
Unbilled utility revenues	88	132
Other receivables	1	—
Receivables sold to third party	250	277
Less: cash proceeds	1	80
Deferred proceeds	249	197
Less: allowance for expected credit losses	13	12
Fair value of deferred proceeds	$236	$185

As of September 30, 2023, outstanding receivables past due under the Receivables Agreement were $18 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Collections	$616	$670	$1,720	$1,731
Write-offs, net of recoveries	5	3	9	6

Effective October 2023, the limit on cash proceeds under the Receivables Agreement is $5 million.

WPL [Member]

Receivables [Line Items]

Receivables

RECEIVABLES

NOTE 4(a) - Accounts Receivable - For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

XML

Investments

9 Months Ended

Sep. 30, 2023

Schedule of Equity Method Investments [Line Items]

Investments

INVESTMENTS

Unconsolidated Equity Investments - Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC Holdings	($12)	($7)	($37)	($29)
Other	(2)	2	(8)	(8)
	($14)	($5)	($45)	($37)

XML

Common Equity

9 Months Ended

Sep. 30, 2023

Common Equity [Line Items]

Common Equity

COMMON EQUITY

Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2023	251,134,966
At-the-market offering program	3,569,937
Shareowner Direct Plan	339,850
Equity-based compensation plans	134,334
Shares outstanding, September 30, 2023	255,179,087

At-the-Market Offering Program - In December 2022, Alliant Energy filed a prospectus supplement under which it may sell up to $225 million of its common stock through an at-the-market offering program. As of September 30, 2023, Alliant Energy issued 3,569,937 shares of common stock through this program and received cash proceeds of $183 million, net of $2 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes.

Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

IPL [Member]

Common Equity [Line Items]

Common Equity

COMMON EQUITY

Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2023	251,134,966
At-the-market offering program	3,569,937
Shareowner Direct Plan	339,850
Equity-based compensation plans	134,334
Shares outstanding, September 30, 2023	255,179,087

At-the-Market Offering Program - In December 2022, Alliant Energy filed a prospectus supplement under which it may sell up to $225 million of its common stock through an at-the-market offering program. As of September 30, 2023, Alliant Energy issued 3,569,937 shares of common stock through this program and received cash proceeds of $183 million, net of $2 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes.

Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL [Member]

Common Equity [Line Items]

Common Equity

COMMON EQUITY

Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2023	251,134,966
At-the-market offering program	3,569,937
Shareowner Direct Plan	339,850
Equity-based compensation plans	134,334
Shares outstanding, September 30, 2023	255,179,087

At-the-Market Offering Program - In December 2022, Alliant Energy filed a prospectus supplement under which it may sell up to $225 million of its common stock through an at-the-market offering program. As of September 30, 2023, Alliant Energy issued 3,569,937 shares of common stock through this program and received cash proceeds of $183 million, net of $2 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes.

Changes in Shareowners’ Equity - A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

XML

Debt

9 Months Ended

Sep. 30, 2023

Debt [Line Items]

Debt

DEBT

NOTE 7(a) Short-term Debt - In March 2023, Alliant Energy, IPL and WPL extended their single credit facility agreement, which currently expires in December 2027, and reallocated credit facility capacity amounts to $450 million for Alliant Energy at the parent company level, $250 million for IPL and $300 million for WPL, within the $1 billion total commitment. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

In January 2023, AEF received $50 million of proceeds from its December 2022 term loan credit agreement, which was classified as “Other short-term borrowings” on Alliant Energy’s balance sheet as of September 30, 2023.

NOTE 7(b) Long-term Debt - In September 2023, IPL issued $300 million of 5.70% senior debentures due 2033. The net proceeds from IPL’s issuance were used to reduce cash amounts received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt, for general corporate purposes and/or were placed in money market fund investments. In June 2023, AEF retired its $400 million 3.75% senior notes. In March 2023, WPL issued $300 million of 4.95% debentures due 2033. WPL’s debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of its solar EGUs.

Convertible Senior Notes - In March 2023, Alliant Energy issued $575 million of 3.875% convertible senior notes (the Notes), which are senior unsecured obligations, and used the net proceeds from the issuance for general corporate purposes. The Notes will mature on March 15, 2026 unless earlier converted or repurchased, and no sinking fund is provided for the Notes. Alliant Energy may not redeem the Notes prior to the maturity date. Holders may convert their Notes at their option at any time prior to the close of business on the business day immediately preceding December 15, 2025 only under the following circumstances:

•during any calendar quarter commencing after the calendar quarter ending on June 30, 2023 (and only during such calendar quarter), if the last reported sale price of Alliant Energy’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day during such period;

•during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price (as defined in the related Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of Alliant Energy’s common stock and the conversion rate on each such trading day; or

•upon the occurrence of specified corporate events.

On or after December 15, 2025 until the close of business on the business day immediately preceding the maturity date, holders may convert all or any portion of their Notes at any time, regardless of the foregoing circumstances. Upon conversion of the Notes, Alliant Energy will pay cash up to the aggregate principal amount of the Notes to be converted and pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at its election, in respect of the remainder, if any, of its conversion obligation in excess of the aggregate principal amount of the Notes being converted.

The initial conversion rate is 15.5461 shares of common stock per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $64.32 per share of Alliant Energy’s common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, Alliant Energy will, in certain circumstances, increase the conversion rate for a holder who elects to convert its Notes in connection with such a corporate event.

If Alliant Energy undergoes a fundamental change (as defined in the related Indenture), then, subject to certain conditions, holders of the Notes may require Alliant Energy to repurchase for cash all or any portion of its Notes at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

As of September 30, 2023, the conditions allowing holders of the Notes to convert their Notes were not met, and as a result, the Notes were classified as “Long-term debt, net” on Alliant Energy’s balance sheet. As of September 30, 2023, the net carrying amount of the Notes was $567 million, with unamortized debt issuance costs of $8 million, and the estimated fair value (Level 2) of the Notes was $556 million. As of September 30, 2023, there were no shares of Alliant Energy’s common stock related to the potential conversion of the Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the Notes.

IPL [Member]

Debt [Line Items]

Debt

DEBT

NOTE 7(a) Short-term Debt - In March 2023, Alliant Energy, IPL and WPL extended their single credit facility agreement, which currently expires in December 2027, and reallocated credit facility capacity amounts to $450 million for Alliant Energy at the parent company level, $250 million for IPL and $300 million for WPL, within the $1 billion total commitment. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

In January 2023, AEF received $50 million of proceeds from its December 2022 term loan credit agreement, which was classified as “Other short-term borrowings” on Alliant Energy’s balance sheet as of September 30, 2023.

NOTE 7(b) Long-term Debt - In September 2023, IPL issued $300 million of 5.70% senior debentures due 2033. The net proceeds from IPL’s issuance were used to reduce cash amounts received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt, for general corporate purposes and/or were placed in money market fund investments. In June 2023, AEF retired its $400 million 3.75% senior notes. In March 2023, WPL issued $300 million of 4.95% debentures due 2033. WPL’s debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of its solar EGUs.

WPL [Member]

Debt [Line Items]

Debt

DEBT

NOTE 7(a) Short-term Debt - In March 2023, Alliant Energy, IPL and WPL extended their single credit facility agreement, which currently expires in December 2027, and reallocated credit facility capacity amounts to $450 million for Alliant Energy at the parent company level, $250 million for IPL and $300 million for WPL, within the $1 billion total commitment. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

In January 2023, AEF received $50 million of proceeds from its December 2022 term loan credit agreement, which was classified as “Other short-term borrowings” on Alliant Energy’s balance sheet as of September 30, 2023.

NOTE 7(b) Long-term Debt - In September 2023, IPL issued $300 million of 5.70% senior debentures due 2033. The net proceeds from IPL’s issuance were used to reduce cash amounts received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt, for general corporate purposes and/or were placed in money market fund investments. In June 2023, AEF retired its $400 million 3.75% senior notes. In March 2023, WPL issued $300 million of 4.95% debentures due 2033. WPL’s debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of its solar EGUs.

XML

Revenues

9 Months Ended

Sep. 30, 2023

Disaggregation of Revenue [Line Items]

Revenues from Contracts with Customers

REVENUES

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

IPL [Member]

Disaggregation of Revenue [Line Items]

Revenues from Contracts with Customers

REVENUES

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

WPL [Member]

Disaggregation of Revenue [Line Items]

Revenues from Contracts with Customers

REVENUES

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

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Income Taxes

9 Months Ended

Sep. 30, 2023

Income Taxes [Line Items]

Income Taxes

INCOME TAXESIncome Tax Rates - Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Deferred Tax Assets and Liabilities -

Carryforwards - At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

Iowa Tax Reform - Pursuant to Iowa tax reform enacted in 2022, in September 2023, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 7.1%, effective January 1, 2024. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2024, which resulted in a $73 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a corresponding decrease in their deferred tax liabilities in the third quarter of 2023. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2024, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and an increase in deferred tax liabilities on Alliant Energy’s balance sheet in the third quarter of 2023. Based on the remeasurement of Alliant Energy parent company’s deferred tax assets in the third quarter of 2022 for the Iowa corporate income tax rate of 8.4% effective January 1, 2023, a charge of $8 million was recorded to income tax expense in Alliant Energy’s income statement in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.

IPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXESIncome Tax Rates - Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Deferred Tax Assets and Liabilities -

Carryforwards - At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

Iowa Tax Reform - Pursuant to Iowa tax reform enacted in 2022, in September 2023, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 7.1%, effective January 1, 2024. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2024, which resulted in a $73 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a corresponding decrease in their deferred tax liabilities in the third quarter of 2023. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2024, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and an increase in deferred tax liabilities on Alliant Energy’s balance sheet in the third quarter of 2023. Based on the remeasurement of Alliant Energy parent company’s deferred tax assets in the third quarter of 2022 for the Iowa corporate income tax rate of 8.4% effective January 1, 2023, a charge of $8 million was recorded to income tax expense in Alliant Energy’s income statement in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.

WPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXESIncome Tax Rates - Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Deferred Tax Assets and Liabilities -

Carryforwards - At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

Iowa Tax Reform - Pursuant to Iowa tax reform enacted in 2022, in September 2023, the Iowa Department of Revenue announced an Iowa corporate income tax rate of 7.1%, effective January 1, 2024. Deferred tax assets and liabilities are measured at the enacted tax rate expected to be applied when temporary differences are to be realized or settled. Given the announcement of the new Iowa corporate income tax rate, Alliant Energy’s and IPL’s deferred tax liabilities were remeasured based upon the new rate effective January 1, 2024, which resulted in a $73 million reduction of Alliant Energy’s and IPL’s tax-related regulatory assets and a corresponding decrease in their deferred tax liabilities in the third quarter of 2023. The reduction in tax-related regulatory assets is expected to provide cost benefits to IPL’s customers in the future. Alliant Energy parent company’s deferred tax assets were remeasured based upon the new rate effective January 1, 2024, which resulted in a charge of $8 million recorded to income tax expense in Alliant Energy’s income statement and an increase in deferred tax liabilities on Alliant Energy’s balance sheet in the third quarter of 2023. Based on the remeasurement of Alliant Energy parent company’s deferred tax assets in the third quarter of 2022 for the Iowa corporate income tax rate of 8.4% effective January 1, 2023, a charge of $8 million was recorded to income tax expense in Alliant Energy’s income statement in the third quarter of 2022. Alliant Energy is currently unable to predict with certainty the timing or amount of any future rate reductions.

XML

Benefit Plans

9 Months Ended

Sep. 30, 2023

Benefit Plans

BENEFIT PLANS

NOTE 10(a) Pension and OPEB Plans -

Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

As of September 30, 2023, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $11 million, $6 million and $5 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years.

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

As of September 30, 2023, 274,960 shares were included in the calculation of diluted EPS related to the nonvested equity awards.

IPL [Member]

Benefit Plans

BENEFIT PLANS

NOTE 10(a) Pension and OPEB Plans -

Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

As of September 30, 2023, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $11 million, $6 million and $5 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years.

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

As of September 30, 2023, 274,960 shares were included in the calculation of diluted EPS related to the nonvested equity awards.

WPL [Member]

Benefit Plans

BENEFIT PLANS

NOTE 10(a) Pension and OPEB Plans -

Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

NOTE 10(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

As of September 30, 2023, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $11 million, $6 million and $5 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years.

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

As of September 30, 2023, 274,960 shares were included in the calculation of diluted EPS related to the nonvested equity awards.

XML

Derivative Instruments

9 Months Ended

Sep. 30, 2023

Derivative Instruments [Line Items]

Derivative Instruments

DERIVATIVE INSTRUMENTS

Commodity Derivatives -

Notional Amounts - As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

During the nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of natural gas, FTR and electricity contracts and lower natural gas prices, partially offset by new FTRs resulting from the annual FTR auction in the second quarter of 2023 operated by MISO. Alliant Energy’s and IPL’s derivative liabilities decreased primarily due to settlement of natural gas contracts. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2023 and December 31, 2022, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that

would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.

Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

Interest Rate Derivative - In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk. Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings. The related interest rate derivative was valued based on quoted prices that utilize current market interest rate forecasts. As of September 30, 2023, $6 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheet. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income/loss. As of September 30, 2023, accumulated other comprehensive income included $4 million of income related to the interest rate swap. For the three and nine months ended September 30, 2023, $1 million and $2 million, respectively, of reductions to interest expense were recorded in Alliant Energy’s income statement related to the interest rate swap.

IPL [Member]

Derivative Instruments [Line Items]

Derivative Instruments

DERIVATIVE INSTRUMENTS

Commodity Derivatives -

Notional Amounts - As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

During the nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of natural gas, FTR and electricity contracts and lower natural gas prices, partially offset by new FTRs resulting from the annual FTR auction in the second quarter of 2023 operated by MISO. Alliant Energy’s and IPL’s derivative liabilities decreased primarily due to settlement of natural gas contracts. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2023 and December 31, 2022, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that

would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.

Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

WPL [Member]

Derivative Instruments [Line Items]

Derivative Instruments

DERIVATIVE INSTRUMENTS

Commodity Derivatives -

Notional Amounts - As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

During the nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s derivative assets decreased primarily due to settlements of natural gas, FTR and electricity contracts and lower natural gas prices, partially offset by new FTRs resulting from the annual FTR auction in the second quarter of 2023 operated by MISO. Alliant Energy’s and IPL’s derivative liabilities decreased primarily due to settlement of natural gas contracts. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At September 30, 2023 and December 31, 2022, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that

would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.

Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

XML

Fair Value Measurements

9 Months Ended

Sep. 30, 2023

Fair Value Measurements

FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

IPL [Member]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

WPL [Member]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

XML

Commitments And Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure

COMMITMENTS AND CONTINGENCIES

NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of solar generation. At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $221 million, $175 million and $46 million, respectively.

NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

NOTE 13(c) Guarantees and Indemnifications -

Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations.

As of September 30, 2023, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2023 and December 31, 2022, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees.

Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees.

Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $51 million as of September 30, 2023 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2023 and December 31, 2022.

NOTE 13(d) Environmental Matters -

Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.

Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Cross-State Air Pollution Rule, Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act.

NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with the Federal Energy Regulatory Commission (FERC) requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.

IPL [Member]

Commitments and Contingencies Disclosure

COMMITMENTS AND CONTINGENCIES

NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of solar generation. At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $221 million, $175 million and $46 million, respectively.

NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

NOTE 13(c) Guarantees and Indemnifications -

Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations.

As of September 30, 2023, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2023 and December 31, 2022, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees.

Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees.

Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $51 million as of September 30, 2023 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2023 and December 31, 2022.

NOTE 13(d) Environmental Matters -

Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.

Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Cross-State Air Pollution Rule, Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act.

NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with the Federal Energy Regulatory Commission (FERC) requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.

WPL [Member]

Commitments and Contingencies Disclosure

COMMITMENTS AND CONTINGENCIES

NOTE 13(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of solar generation. At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $221 million, $175 million and $46 million, respectively.

NOTE 13(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

NOTE 13(c) Guarantees and Indemnifications -

Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations.

As of September 30, 2023, the currently known partnership obligations for the abandonment obligations are estimated at $58 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $58 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, as of both September 30, 2023 and December 31, 2022, a liability of $5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees.

Whiting Petroleum completed a business combination with Oasis Petroleum Inc. in July 2022. The combined operations are now known as Chord Energy Corporation. The business combination is not expected to affect the scope of the Whiting Petroleum affiliate’s obligations to Alliant Energy or Alliant Energy’s related guarantees.

Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $51 million as of September 30, 2023 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of September 30, 2023 and December 31, 2022.

NOTE 13(d) Environmental Matters -

Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.

Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Cross-State Air Pollution Rule, Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of greenhouse gases, including the Clean Air Act.

NOTE 13(e) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with the Federal Energy Regulatory Commission (FERC) requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC Midwest LLC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In August 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings, which may result in additional changes to the base return on equity authorized for the MISO transmission owners. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.

XML

Segments Of Business

9 Months Ended

Sep. 30, 2023

Segment Reporting Information [Line Items]

Segments Of Business

SEGMENTS OF BUSINESS

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

IPL [Member]

Segment Reporting Information [Line Items]

Segments Of Business

SEGMENTS OF BUSINESS

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

WPL [Member]

Segment Reporting Information [Line Items]

Segments Of Business

SEGMENTS OF BUSINESS

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

XML

Related Parties

9 Months Ended

Sep. 30, 2023

Related Party Transactions [Line Items]

Related Parties

RELATED PARTIES

Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC billings to WPL	$41	$38	$119	$107
WPL billings to ATC	5	6	16	14

WPL owed ATC net amounts of $9 million as of September 30, 2023 and $10 million as of December 31, 2022.

IPL [Member]

Related Party Transactions [Line Items]

Related Parties

RELATED PARTIES

Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

WPL [Member]

Related Party Transactions [Line Items]

Related Parties

RELATED PARTIES

Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC billings to WPL	$41	$38	$119	$107
WPL billings to ATC	5	6	16	14

WPL owed ATC net amounts of $9 million as of September 30, 2023 and $10 million as of December 31, 2022.

XML

Pay vs Performance Disclosure - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income	$ 582	$ 579

XML

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

XML

Summary Of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2023
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Cash and Cash Equivalents	At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.
IPL [Member]
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Cash and Cash Equivalents	At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.
WPL [Member]
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2022 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the nine months ended September 30, 2023 are not necessarily indicative of results that may be expected for the year ending December 31, 2023.
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Cash and Cash Equivalents	At September 30, 2023, Alliant Energy’s, IPL’s and WPL’s cash and cash equivalents included $189 million, $180 million and $9 million of money market fund investments, respectively, with weighted average interest rates of 5%.

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Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2023

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

IPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

WPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$919	$929	$825	$848	$94	$81
Pension and OPEB costs	371	392	187	197	184	195
Assets retired early	282	70	267	53	15	17
Asset retirement obligations (AROs)	199	151	155	110	44	41
Commodity cost recovery	138	160	11	1	127	159
Derivatives	72	84	27	48	45	36
IPL’s Duane Arnold Energy Center PPA amendment	48	66	48	66	—	—
WPL’s Western Wisconsin gas distribution expansion investments	46	48	—	—	46	48
Other	194	146	70	63	124	83
	$2,269	$2,046	$1,590	$1,386	$679	$660

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Tax-related	$569	$579	$301	$303	$268	$276
Cost of removal obligations	397	398	249	259	148	139
Derivatives	91	210	52	115	39	95
Commodity cost recovery	41	40	11	38	30	2
WPL’s West Riverside liquidated damages	9	32	—	—	9	32
Electric transmission cost recovery	6	20	6	10	—	10
Other	74	45	36	29	38	16
	$1,187	$1,324	$655	$754	$532	$570

XML

Receivables (Tables)

9 Months Ended

Sep. 30, 2023

Receivables [Line Items]

Gross Write-offs For Accounts Receivable

For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

Maximum And Average Outstanding Cash Proceeds

IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Maximum outstanding aggregate cash proceeds	$94	$36	$110	$66
Average outstanding aggregate cash proceeds	46	3	68	8

Attributes of Receivables Sold Under the Receivables Agreement

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

	September 30, 2023	December 31, 2022
Customer accounts receivable	$161	$145
Unbilled utility revenues	88	132
Other receivables	1	—
Receivables sold to third party	250	277
Less: cash proceeds	1	80
Deferred proceeds	249	197
Less: allowance for expected credit losses	13	12
Fair value of deferred proceeds	$236	$185

Additional Attributes Of Receivables Sold Under The Receivables Agreement

Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Collections	$616	$670	$1,720	$1,731
Write-offs, net of recoveries	5	3	9	6

IPL [Member]

Receivables [Line Items]

Gross Write-offs For Accounts Receivable

For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

Maximum And Average Outstanding Cash Proceeds

IPL’s maximum and average outstanding cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Maximum outstanding aggregate cash proceeds	$94	$36	$110	$66
Average outstanding aggregate cash proceeds	46	3	68	8

Attributes of Receivables Sold Under the Receivables Agreement

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

	September 30, 2023	December 31, 2022
Customer accounts receivable	$161	$145
Unbilled utility revenues	88	132
Other receivables	1	—
Receivables sold to third party	250	277
Less: cash proceeds	1	80
Deferred proceeds	249	197
Less: allowance for expected credit losses	13	12
Fair value of deferred proceeds	$236	$185

Additional Attributes Of Receivables Sold Under The Receivables Agreement

Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
Collections	$616	$670	$1,720	$1,731
Write-offs, net of recoveries	5	3	9	6

WPL [Member]

Receivables [Line Items]

Gross Write-offs For Accounts Receivable

For the three and nine months ended September 30, 2023, Alliant Energy’s, IPL’s and WPL’s gross write-offs for accounts receivable were as follows (in millions):

	Originated in 2022		Originated in 2023
	Three Months	Nine Months	Three Months	Nine Months
Alliant Energy	$3	$11	$6	$8
IPL	2	7	4	5
WPL	1	4	2	3

XML

Investments (Tables)

9 Months Ended

Sep. 30, 2023

Schedule of Equity Method Investments [Line Items]

Unconsolidated Equity Investments

Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC Holdings	($12)	($7)	($37)	($29)
Other	(2)	2	(8)	(8)
	($14)	($5)	($45)	($37)

XML

Common Equity (Tables)

9 Months Ended

Sep. 30, 2023

Schedule of Capitalization, Equity [Line Items]

Common Share Activity

A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2023	251,134,966
At-the-market offering program	3,569,937
Shareowner Direct Plan	339,850
Equity-based compensation plans	134,334
Shares outstanding, September 30, 2023	255,179,087

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

IPL [Member]

Schedule of Capitalization, Equity [Line Items]

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL [Member]

Schedule of Capitalization, Equity [Line Items]

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$3	$2,854	$3,606	$3	($14)	$—	$6,452
Net income attributable to Alliant Energy common shareowners			259				259
Common stock dividends ($0.4525 per share)			(115)				(115)
At-the-market offering program and Shareowner Direct Plan issuances		125					125
Equity-based compensation plans and other		3			1		4
Other comprehensive income, net of tax				1			1
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$3	$2,759	$3,387	$—	($12)	$29	$6,166
Net income attributable to Alliant Energy common shareowners			227				227
Common stock dividends ($0.4275 per share)			(106)				(106)
Shareowner Direct Plan issuances		6					6
Equity-based compensation plans and other		2			(1)		1
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

Alliant Energy	Total Alliant Energy Common Equity
				Accumulated	Shares in
		Additional		Other	Deferred
	Common	Paid-In	Retained	Comprehensive	Compensation	Noncontrolling	Total
	Stock	Capital	Earnings	Income	Trust	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$3	$2,777	$3,509	$—	($13)	$—	$6,276
Net income attributable to Alliant Energy common shareowners			582				582
Common stock dividends ($1.3575 per share)			(341)				(341)
At-the-market offering program and Shareowner Direct Plan issuances		201					201
Equity-based compensation plans and other		4					4
Other comprehensive income, net of tax				4			4
Ending balance, September 30, 2023	$3	$2,982	$3,750	$4	($13)	$—	$6,726
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$3	$2,749	$3,250	$—	($12)	$—	$5,990
Net income attributable to Alliant Energy common shareowners			579				579
Common stock dividends ($1.2825 per share)			(322)				(322)
Shareowner Direct Plan issuances		19					19
Equity-based compensation plans and other		(1)	1		(1)		(1)
Contributions from noncontrolling interest						29	29
Distributions to noncontrolling interest						(29)	(29)
Ending balance, September 30, 2022	$3	$2,767	$3,508	$—	($13)	$—	$6,265

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$33	$2,847	$989	$3,869
Net income			170	170
Common stock dividends			(70)	(70)
Capital contributions from parent		20		20
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$33	$2,807	$942	$3,782
Net income			154	154
Common stock dividends			(80)	(80)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

IPL		Additional		Total
	Common	Paid-In	Retained	Common
	Stock	Capital	Earnings	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$33	$2,807	$968	$3,808
Net income			331	331
Common stock dividends			(210)	(210)
Capital contributions from parent		60		60
Ending balance, September 30, 2023	$33	$2,867	$1,089	$3,989
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$33	$2,807	$929	$3,769
Net income			327	327
Common stock dividends			(240)	(240)
Ending balance, September 30, 2022	$33	$2,807	$1,016	$3,856

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Three Months Ended September 30, 2023
Beginning balance, June 30, 2023	$66	$2,413	$1,260	$—	$3,739
Net income			107		107
Common stock dividends			(46)		(46)
Capital contributions from parent		65			65
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Three Months Ended September 30, 2022
Beginning balance, June 30, 2022	$66	$1,968	$1,120	$29	$3,183
Net income			91		91
Common stock dividends			(44)		(44)
Capital contributions from parent		155			155
Distributions to noncontrolling interest				(29)	(29)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

WPL	Total WPL Common Equity
		Additional
	Common	Paid-In	Retained	Noncontrolling	Total
	Stock	Capital	Earnings	Interest	Equity
Nine Months Ended September 30, 2023
Beginning balance, December 31, 2022	$66	$2,233	$1,192	$—	$3,491
Net income			267		267
Common stock dividends			(138)		(138)
Capital contributions from parent		245			245
Ending balance, September 30, 2023	$66	$2,478	$1,321	$—	$3,865
Nine Months Ended September 30, 2022
Beginning balance, December 31, 2021	$66	$1,704	$1,053	$—	$2,823
Net income			247		247
Common stock dividends			(133)		(133)
Capital contributions from parent		420			420
Contributions from noncontrolling interest				29	29
Distributions to noncontrolling interest				(29)	(29)
Other		(1)			(1)
Ending balance, September 30, 2022	$66	$2,123	$1,167	$—	$3,356

XML

Debt (Tables)

9 Months Ended

Sep. 30, 2023

Short-term Debt [Line Items]

Other Short-Term Borrowings

Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

IPL [Member]

Short-term Debt [Line Items]

Other Short-Term Borrowings

Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

WPL [Member]

Short-term Debt [Line Items]

Other Short-Term Borrowings

Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):

September 30, 2023	Alliant Energy	IPL	WPL
Amount outstanding	$451	$—	$120
Weighted average interest rates	5.5%	—%	5.4%
Available credit facility capacity	$549	$250	$180

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Maximum amount outstanding (based on daily outstanding balances)	$474	$449	$7	$—	$125	$251
Average amount outstanding (based on daily outstanding balances)	$440	$353	$—	$—	$86	$110
Weighted average interest rates	5.5%	2.4%	5.5%	—%	5.4%	2.0%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)	$793	$577	$70	$—	$349	$252
Average amount outstanding (based on daily outstanding balances)	$367	$377	$2	$—	$135	$160
Weighted average interest rates	5.1%	1.2%	5.3%	—%	4.9%	0.9%

XML

Revenues (Tables)

9 Months Ended

Sep. 30, 2023

Disaggregation of Revenue [Line Items]

Disaggregation of Revenue

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

IPL [Member]

Disaggregation of Revenue [Line Items]

Disaggregation of Revenue

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

WPL [Member]

Disaggregation of Revenue [Line Items]

Disaggregation of Revenue

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

	Alliant Energy		IPL		WPL
Three Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$374	$376	$209	$222	$165	$154
Retail - commercial	241	243	158	165	83	78
Retail - industrial	280	289	153	172	127	117
Wholesale	59	68	21	19	38	49
Bulk power and other	41	63	10	18	31	45
Total Electric Utility	995	1,039	551	596	444	443
Gas Utility:
Retail - residential	23	28	14	14	9	14
Retail - commercial	12	18	9	8	3	10
Retail - industrial	2	4	2	3	—	1
Transportation/other	10	12	6	8	4	4
Total Gas Utility	47	62	31	33	16	29
Other Utility:
Steam	11	9	11	9	—	—
Other utility	2	2	1	2	1	—
Total Other Utility	13	11	12	11	1	—
Non-Utility and Other:
Travero and other	22	23	—	—	—	—
Total Non-Utility and Other	22	23	—	—	—	—
Total revenues	$1,077	$1,135	$594	$640	$461	$472

	Alliant Energy		IPL		WPL
Nine Months Ended September 30	2023	2022	2023	2022	2023	2022
Electric Utility:
Retail - residential	$943	$956	$503	$529	$440	$427
Retail - commercial	627	628	399	411	228	217
Retail - industrial	740	743	389	418	351	325
Wholesale	154	168	47	49	107	119
Bulk power and other	98	129	32	31	66	98
Total Electric Utility	2,562	2,624	1,370	1,438	1,192	1,186
Gas Utility:
Retail - residential	233	237	131	127	102	110
Retail - commercial	122	127	65	62	57	65
Retail - industrial	12	15	8	10	4	5
Transportation/other	33	39	20	25	13	14
Total Gas Utility	400	418	224	224	176	194
Other Utility:
Steam	32	29	32	29	—	—
Other utility	6	6	4	5	2	1
Total Other Utility	38	35	36	34	2	1
Non-Utility and Other:
Travero and other	66	70	—	—	—	—
Total Non-Utility and Other	66	70	—	—	—	—
Total revenues	$3,066	$3,147	$1,630	$1,696	$1,370	$1,381

XML

Income Taxes (Tables)

9 Months Ended

Sep. 30, 2023

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Summary Of Tax Credit Carryforwards

At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

IPL [Member]

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Summary Of Tax Credit Carryforwards

At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

WPL [Member]

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

Overall effective income tax rates for the three and nine months ended September 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences.

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Overall income tax rate	2%	6%	1%	4%	(22%)	(12%)	(20%)	(14%)	16%	15%	15%	17%

Summary Of Tax Credit Carryforwards

At September 30, 2023, the carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
State net operating losses	2025-2043	$431	$6	$1
Federal tax credits	2031-2043	737	520	208

XML

Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2023

Defined Benefit Plan Disclosure [Line Items]

Net Periodic Benefit Costs

The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

Recognized Compensation Expense And Income Tax Benefits

A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

Schedule Of Equity-based Compensation Plans Activity

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

IPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Net Periodic Benefit Costs

The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

Recognized Compensation Expense And Income Tax Benefits

A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

Schedule Of Equity-based Compensation Plans Activity

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

WPL [Member]

Defined Benefit Plan Disclosure [Line Items]

Net Periodic Benefit Costs

The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and nine months ended September 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
Alliant Energy	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$2	$3	$4	$7	$1	$—	$2	$2
Interest cost	12	9	35	27	3	1	7	4
Expected return on plan assets	(14)	(18)	(40)	(52)	(2)	—	(4)	(3)
Amortization of prior service credit	(1)	—	(1)	—	—	—	—	—
Amortization of actuarial loss	7	8	21	24	—	1	1	2
	$6	$2	$19	$6	$2	$2	$6	$5

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
IPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$1	$2	$4	$—	$—	$—	$1
Interest cost	6	4	16	12	1	1	3	2
Expected return on plan assets	(6)	(7)	(19)	(23)	(1)	(1)	(3)	(3)
Amortization of actuarial loss	2	3	8	10	—	—	1	—
	$2	$1	$7	$3	$—	$—	$1	$—

	Defined Benefit Pension Plans				OPEB Plans
	Three Months		Nine Months		Three Months		Nine Months
WPL	2023	2022	2023	2022	2023	2022	2023	2022
Service cost	$—	$—	$1	$2	$1	$—	$1	$—
Interest cost	5	4	15	12	1	1	3	2
Expected return on plan assets	(5)	(7)	(16)	(23)	(1)	—	(1)	—
Amortization of actuarial loss	3	4	10	12	—	—	—	1
	$3	$1	$10	$3	$1	$1	$3	$3

Recognized Compensation Expense And Income Tax Benefits

A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and nine months ended September 30 was as follows (in millions):

	Alliant Energy				IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022	2023	2022
Compensation expense	$4	$3	$10	$9	$2	$2	$5	$5	$2	$1	$4	$4
Income tax benefits	1	1	3	3	1	—	1	1	—	—	1	1

Schedule Of Equity-based Compensation Plans Activity

For the nine months ended September 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

		Weighted Average
	Grants	Grant Date Fair Value
Performance shares	108,513	$55.68
Performance restricted stock units	123,990	52.71
Restricted stock units	105,982	52.77

XML

Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2023

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Fair Value Of Financial Instruments

Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

Balance Sheet Offsetting

However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

IPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Fair Value Of Financial Instruments

Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

Balance Sheet Offsetting

However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

WPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of September 30, 2023, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	1,661	2023-2026	18,122	2023-2024	180,519	2023-2032	370	2023
IPL	746	2023-2026	8,078	2023-2024	85,457	2023-2030	217	2023
WPL	915	2023-2026	10,044	2023-2024	95,062	2023-2032	153	2023

Fair Value Of Financial Instruments

Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Current derivative assets	$67	$111	$51	$69	$16	$42
Non-current derivative assets	62	126	34	69	28	57
Current derivative liabilities	32	59	15	40	17	19
Non-current derivative liabilities	34	20	6	6	28	14

Balance Sheet Offsetting

However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
September 30, 2023
Derivative assets	$129	$108	$85	$73	$44	$35
Derivative liabilities	66	45	21	9	45	36
December 31, 2022
Derivative assets	237	193	138	108	99	85
Derivative liabilities	79	35	46	16	33	19

XML

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

Statement [Line Items]

Fair Value Measurements

Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Fair Value Measurements Using Significant Unobservable Inputs

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Fair Value Of Net Derivative Assets (Liabilities)

The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

IPL [Member]

Statement [Line Items]

Fair Value Measurements

Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Fair Value Measurements Using Significant Unobservable Inputs

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Fair Value Of Net Derivative Assets (Liabilities)

The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

WPL [Member]

Statement [Line Items]

Fair Value Measurements

Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Fair Value Measurements Using Significant Unobservable Inputs

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Fair Value Of Net Derivative Assets (Liabilities)

The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

XML

Commitments And Contingencies (Tables)

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies [Line Items]

Other Purchase Commitments

At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

MGP Site Estimated Future Costs And Recorded Liabilities

At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

IPL [Member]

Commitments and Contingencies [Line Items]

Other Purchase Commitments

At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

MGP Site Estimated Future Costs And Recorded Liabilities

At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

WPL [Member]

Commitments and Contingencies [Line Items]

Other Purchase Commitments

At September 30, 2023, related minimum future commitments were as follows (in millions):

	Alliant Energy	IPL	WPL
Natural gas	$962	$436	$526
Coal	188	108	80
Other (a)	125	52	25
	$1,275	$596	$631

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2023.

MGP Site Estimated Future Costs And Recorded Liabilities

At September 30, 2023, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

	Alliant Energy			IPL			WPL
Range of estimated future costs	$9	-	$36	$5	-	$11	$4	-	$25
Current and non-current environmental liabilities	$18			$8			$10

XML

Segments Of Business (Tables)

9 Months Ended

Sep. 30, 2023

Segment Reporting Information [Line Items]

Schedule Of Segments Of Business

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

IPL [Member]

Segment Reporting Information [Line Items]

Schedule Of Segments Of Business

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

WPL [Member]

Segment Reporting Information [Line Items]

Schedule Of Segments Of Business

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s business segments is as follows. Intersegment revenues were not material to their respective operations.

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Three Months Ended September 30, 2023
Revenues	$995	$47	$13	$1,055	$22	$1,077
Operating income (loss)	319	(4)	—	315	7	322
Net income (loss) attributable to Alliant Energy common shareowners				277	(18)	259
Three Months Ended September 30, 2022
Revenues	$1,039	$62	$11	$1,112	$23	$1,135
Operating income (loss)	304	(3)	1	302	7	309
Net income (loss) attributable to Alliant Energy common shareowners				245	(18)	227

Alliant Energy					ATC Holdings,	Alliant
	Utility				Non-Utility,	Energy
	Electric	Gas	Other	Total	Parent and Other	Consolidated
	(in millions)
Nine Months Ended September 30, 2023
Revenues	$2,562	$400	$38	$3,000	$66	$3,066
Operating income	682	48	12	742	18	760
Net income (loss) attributable to Alliant Energy common shareowners				598	(16)	582
Nine Months Ended September 30, 2022
Revenues	$2,624	$418	$35	$3,077	$70	$3,147
Operating income	680	62	4	746	23	769
Net income attributable to Alliant Energy common shareowners				574	5	579

IPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$551	$31	$12	$594
Operating income (loss)	171	(2)	4	173
Net income				170
Three Months Ended September 30, 2022
Revenues	$596	$33	$11	$640
Operating income (loss)	174	(3)	—	171
Net income				154
Nine Months Ended September 30, 2023
Revenues	$1,370	$224	$36	$1,630
Operating income	342	25	12	379
Net income				331
Nine Months Ended September 30, 2022
Revenues	$1,438	$224	$34	$1,696
Operating income	353	33	3	389
Net income				327

WPL	Electric	Gas	Other	Total
	(in millions)
Three Months Ended September 30, 2023
Revenues	$444	$16	$1	$461
Operating income (loss)	148	(2)	(4)	142
Net income				107
Three Months Ended September 30, 2022
Revenues	$443	$29	$—	$472
Operating income	130	—	1	131
Net income				91
Nine Months Ended September 30, 2023
Revenues	$1,192	$176	$2	$1,370
Operating income	340	23	—	363
Net income				267
Nine Months Ended September 30, 2022
Revenues	$1,186	$194	$1	$1,381
Operating income	327	29	1	357
Net income				247

XML

Related Parties (Tables)

9 Months Ended

Sep. 30, 2023

Related Party Transactions [Line Items]

Services Provided, Sales Credited And Purchases

The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net Intercompany Payables

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

Related Amounts Billed Between Parties

The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC billings to WPL	$41	$38	$119	$107
WPL billings to ATC	5	6	16	14

IPL [Member]

Related Party Transactions [Line Items]

Services Provided, Sales Credited And Purchases

The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net Intercompany Payables

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

WPL [Member]

Related Party Transactions [Line Items]

Services Provided, Sales Credited And Purchases

The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):

	IPL				WPL
	Three Months		Nine Months		Three Months		Nine Months
	2023	2022	2023	2022	2023	2022	2023	2022
Corporate Services billings	$46	$45	$134	$136	$40	$39	$120	$117
Sales credited	3	11	11	11	23	31	45	62
Purchases billed	133	119	320	342	5	42	21	103

Net Intercompany Payables

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2023	December 31, 2022	September 30, 2023	December 31, 2022
Net payables to Corporate Services	$136	$103	$71	$56

Related Amounts Billed Between Parties

The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months		Nine Months
	2023	2022	2023	2022
ATC billings to WPL	$41	$38	$119	$107
WPL billings to ATC	5	6	16	14

XML

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Money market fund investments	$ 189	$ 10
Money market fund investments weighted-average interest rate, percentage	5.00%
IPL [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Money market fund investments	$ 180	$ 10
Money market fund investments weighted-average interest rate, percentage	5.00%
WPL [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Money market fund investments	$ 9
Money market fund investments weighted-average interest rate, percentage	5.00%

XML

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Regulatory Matters [Line Items]
Regulatory assets	$ 2,269	$ 2,046
IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	1,590	1,386
WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	679	660
Assets retired early [Member]
Regulatory Matters [Line Items]
Regulatory assets	282	70
Assets retired early [Member] | IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	267	53
Assets retired early [Member] | WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	15	$ 17
Assets retired early [Member] | Lansing Generating Station
Regulatory Matters [Line Items]
Regulatory assets	221
Assets retired early [Member] | Lansing Generating Station | IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets	$ 221

XML

Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Regulatory Assets [Line Items]
Regulatory assets	$ 2,269	$ 2,046
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	919	929
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	371	392
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	282	70
Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	199	151
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	138	160
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	72	84
IPL's Duane Arnold Energy Center PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	48	66
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	46	48
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	194	146
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,590	1,386
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	825	848
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	187	197
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	267	53
IPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	155	110
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	11	1
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	27	48
IPL [Member] | IPL's Duane Arnold Energy Center PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	48	66
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	70	63
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	679	660
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	94	81
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	184	195
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	15	17
WPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	44	41
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	127	159
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	45	36
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	46	48
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 124	$ 83

XML

Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,187	$ 1,324
Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	569	579
Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	397	398
Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	91	210
Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	41	40
WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	9	32
Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	6	20
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	74	45
IPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	655	754
IPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	301	303
IPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	249	259
IPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	52	115
IPL [Member] | Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	11	38
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	6	10
IPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	36	29
WPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	532	570
WPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	268	276
WPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	148	139
WPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	39	95
WPL [Member] | Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	30	2
WPL [Member] | WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	9	32
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	10
WPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 38	$ 16

XML

Property, Plant and Equipment (Narrative) (Details)	Sep. 30, 2023
WPL [Member] | West Riverside Energy Center [Member]
Property, Plant and Equipment [Line Items]
Ownership interest, percent	73.80%

XML

Receivables (Narrative) (Details) - Receivables Sold [Member] - IPL [Member] - USD ($) $ in Millions	Dec. 31, 2023	Oct. 31, 2023	Sep. 30, 2023
Receivables [Line Items]
Available capacity			$ 109
Subsequent Event [Member]
Receivables [Line Items]
Available capacity	$ 110	$ 5
Financial Asset, Past Due [Member]
Receivables [Line Items]
Outstanding receivables past due			$ 18

XML

Receivables (Gross Write-offs For Accounts Receivable) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Gross write-offs for accounts receivable, originated in 2022	$ 3	$ 11
Gross write-offs for accounts receivable, originated in 2023	6	8
IPL [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross write-offs for accounts receivable, originated in 2022	2	7
Gross write-offs for accounts receivable, originated in 2023	4	5
WPL [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross write-offs for accounts receivable, originated in 2022	1	4
Gross write-offs for accounts receivable, originated in 2023	$ 2	$ 3

XML

Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Maximum [Member]
Receivables [Line Items]
Maximum outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 94	$ 36	$ 110	$ 66
Average [Member]
Receivables [Line Items]
Average outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 46	$ 3	$ 68	$ 8

XML

Receivables (Receivables Sold Under The Agreement) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Receivables [Line Items]
Fair value of deferred proceeds	$ 236	$ 185
IPL [Member]
Receivables [Line Items]
Fair value of deferred proceeds	236	185
Receivables Sold [Member] | IPL [Member]
Receivables [Line Items]
Customer accounts receivable	161	145
Unbilled utility revenues	88	132
Other receivables	1	0
Receivables sold to third party	250	277
Less: cash proceeds	1	80
Deferred proceeds	249	197
Less: allowance for expected credit losses	13	12
Fair value of deferred proceeds	$ 236	$ 185

XML

Receivables (Additional Attributes Of Receivables Sold Under The Agreement) (Details) - IPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Receivables [Line Items]
Collections	$ 616	$ 670	$ 1,720	$ 1,731
Write-offs, net of recoveries	$ 5	$ 3	$ 9	$ 6

XML

Investments (Unconsolidated Equity Investments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	$ (14)	$ (5)	$ (45)	$ (37)
ATC Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	(12)	(7)	(37)	(29)
Other [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	(2)	2	(8)	(8)
Total [Member]
Schedule of Equity Method Investments [Line Items]
Equity (income) loss from unconsolidated investments, net	$ (14)	$ (5)	$ (45)	$ (37)

XML

Common Equity (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023
Common Equity [Line Items]
Proceeds from issuance of common stock, net	$ 125	$ 6	$ 201	$ 19
At The Market Offering Program [Member]
Common Equity [Line Items]
Common stock issued during period, At-the-market offering program (in shares)			3,569,937
Proceeds from issuance of common stock, net			$ 183
Fees and commissions from issuance of common stock			$ 2
At The Market Offering Program [Member] | Forecast [Member]
Common Equity [Line Items]
Maximum aggregate gross sales price of common stock that can be offered and sold					$ 225

XML

Common Equity (Common Share Activity) (Details)	9 Months Ended
	Sep. 30, 2023 shares
Common Stock Oustanding [Roll Forward]
Shares outstanding, January 1, 2023 (in shares)	251,134,966
Shareowner Direct Plan (in shares)	339,850
Equity-based compensation plans (in shares)	134,334
Shares outstanding, September 30, 2023 (in shares)	255,179,087
At The Market Offering Program [Member]
Common Stock Oustanding [Roll Forward]
Common stock issued during period, At-the-market offering program (in shares)	3,569,937

XML

Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 6,276
Beginning balance	$ 6,452	$ 6,166	6,276	$ 5,990
Net income attributable to common shareowners	259	227	582	579
Net income			582	579
Common stock dividends	(115)	(106)	(341)	(322)
At-the-market offering program and Shareowner Direct Plan issuances	125	6	201	19
Equity-based compensation plans and other	4	1	4	(1)
Other comprehensive income, net of tax	1		4
Contributions from noncontrolling interest			0	29
Distributions to noncontrolling interest		(29)	0	(29)
Ending balance	6,726		6,726
Ending balance	$ 6,726	$ 6,265	$ 6,726	$ 6,265
Common stock dividends (in dollars per share)	$ 0.4525	$ 0.4275	$ 1.3575	$ 1.2825
Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 3	$ 3	$ 3	$ 3
Ending balance	3	3	3	3
Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,854	2,759	2,777	2,749
At-the-market offering program and Shareowner Direct Plan issuances	125	6	201	19
Equity-based compensation plans and other	3	2	4	(1)
Ending balance	2,982	2,767	2,982	2,767
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,606	3,387	3,509	3,250
Net income attributable to common shareowners	259	227	582	579
Common stock dividends	(115)	(106)	(341)	(322)
Equity-based compensation plans and other				1
Ending balance	3,750	3,508	3,750	3,508
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3	0	0	0
Other comprehensive income, net of tax	1		4
Ending balance	4	0	4	0
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(14)	(12)	(13)	(12)
Equity-based compensation plans and other	1	(1)		(1)
Ending balance	(13)	(13)	(13)	(13)
Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	29	0	0
Contributions from noncontrolling interest				29
Distributions to noncontrolling interest		(29)		(29)
Ending balance	0	0	0	0
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,808
Beginning balance	3,869	3,782	3,808	3,769
Net income	170	154	331	327
Common stock dividends	(70)	(80)	(210)	(240)
Capital contributions from parent	20		60	0
Ending balance	3,989		3,989
Ending balance	3,989	3,856	3,989	3,856
IPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	33	33	33	33
Ending balance	33	33	33	33
IPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,847	2,807	2,807	2,807
Capital contributions from parent	20		60
Ending balance	2,867	2,807	2,867	2,807
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	989	942	968	929
Net income	170	154	331	327
Common stock dividends	(70)	(80)	(210)	(240)
Ending balance	1,089	1,016	1,089	1,016
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,491
Beginning balance	3,739	3,183	3,491	2,823
Net income	107	91	267	247
Common stock dividends	(46)	(44)	(138)	(133)
Equity-based compensation plans and other				(1)
Capital contributions from parent	65	155	245	420
Contributions from noncontrolling interest			0	29
Distributions to noncontrolling interest		(29)	0	(29)
Ending balance	3,865		3,865
Ending balance	3,865	3,356	3,865	3,356
WPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	66	66	66	66
Ending balance	66	66	66	66
WPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,413	1,968	2,233	1,704
Equity-based compensation plans and other				(1)
Capital contributions from parent	65	155	245	420
Ending balance	2,478	2,123	2,478	2,123
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,260	1,120	1,192	1,053
Net income	107	91	267	247
Common stock dividends	(46)	(44)	(138)	(133)
Ending balance	1,321	1,167	1,321	1,167
WPL [Member] | Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	29	0	0
Contributions from noncontrolling interest				29
Distributions to noncontrolling interest		(29)		(29)
Ending balance	$ 0	$ 0	$ 0	$ 0

XML

Debt (Narrative) (Details)	9 Months Ended
	Sep. 30, 2023 USD ($) Integer $ / shares shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Debt [Line Items]
Line of credit facility, current borrowing capacity	$ 1,000,000,000
Payments to retire long-term debt	404,000,000	$ 379,000,000
Long-term debt, fair value	7,863,000,000		$ 7,339,000,000
Parent Company [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	450,000,000
IPL [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	250,000,000
Long-term debt, fair value	3,422,000,000		3,228,000,000
WPL [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	300,000,000
Long-term debt, fair value	2,722,000,000		$ 2,542,000,000
Term Loan Credit Agreement [Member] | Term loan credit agreement through March 2024 [Member] | Alliant Energy Finance LLC [Member]
Debt [Line Items]
Long-term debt	50,000,000
Senior Debentures [Member] | 5.70% senior debenture, due 2033 | IPL [Member]
Debt [Line Items]
Long-term debt	$ 300,000,000
Interest rate, percent	5.70%
Senior Notes [Member] | 3.75% senior notes, due 2023 [Member] | Alliant Energy Finance LLC [Member]
Debt [Line Items]
Payments to retire long-term debt	$ 400,000,000
Interest rate, percent	3.75%
Debentures [Member] | 4.95% debenture, due 2033 [Member] | WPL [Member]
Debt [Line Items]
Long-term debt	$ 300,000,000
Interest rate, percent	4.95%
Convertible Senior Notes [Member]
Debt [Line Items]
Trading days | Integer	20
Trading days consecutive | Integer	30
Convertible Senior Notes [Member] | 3.875% convertible senior notes, due 2026 [Member]
Debt [Line Items]
Long-term debt	$ 575,000,000
Interest rate, percent	3.875%
Trading days | Integer	5
Trading days consecutive | Integer	10
Principal amount of Notes conversion rate applied to	$ 1,000
Initial conversion ratio	15.5461
Initial conversion price | $ / shares	$ 64.32
Fundamental change repurchase conversion price, percent	100.00%
Long-term debt, carrying value	$ 567,000,000
Unamortized debt issuance costs	8,000,000
Long-term debt, fair value	$ 556,000,000
Shares included in diluted earnings per share (in shares) | shares	0
Convertible Senior Notes [Member] | 3.875% convertible senior notes, due 2026 [Member] | Maximum [Member]
Debt [Line Items]
Conversion price, percent	130.00%
Convertible Senior Notes [Member] | 3.875% convertible senior notes, due 2026 [Member] | Minimum [Member]
Debt [Line Items]
Conversion price, percent	98.00%

XML

Debt (Credit Facilities) (Details) $ in Millions	Sep. 30, 2023 USD ($)
Debt [Line Items]
Amount outstanding	$ 451
Weighted average interest rates	5.50%
Available credit facility capacity	$ 549
IPL [Member]
Debt [Line Items]
Amount outstanding	$ 0
Weighted average interest rates	0.00%
Available credit facility capacity	$ 250
WPL [Member]
Debt [Line Items]
Amount outstanding	$ 120
Weighted average interest rates	5.40%
Available credit facility capacity	$ 180

XML

Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 474	$ 449	$ 793	$ 577
Average amount outstanding (based on daily outstanding balances)	$ 440	$ 353	$ 367	$ 377
Weighted average interest rates	5.50%	2.40%	5.10%	1.20%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 7	$ 0	$ 70	$ 0
Average amount outstanding (based on daily outstanding balances)	$ 0	$ 0	$ 2	$ 0
Weighted average interest rates	5.50%	0.00%	5.30%	0.00%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 125	$ 251	$ 349	$ 252
Average amount outstanding (based on daily outstanding balances)	$ 86	$ 110	$ 135	$ 160
Weighted average interest rates	5.40%	2.00%	4.90%	0.90%

XML

Revenue (Disaggregation of Revenues) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,077	$ 1,135	$ 3,066	$ 3,147
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	995	1,039	2,562	2,624
Electric [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	374	376	943	956
Electric [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	241	243	627	628
Electric [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	280	289	740	743
Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	59	68	154	168
Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	41	63	98	129
Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	47	62	400	418
Gas [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	23	28	233	237
Gas [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12	18	122	127
Gas [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	4	12	15
Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10	12	33	39
Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13	11	38	35
Other Utility [Member] | Steam [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11	9	32	29
Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2	6	6
Non-utility and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	22	23	66	70
Non-utility and Other [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	22	23	66	70
IPL [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	594	640	1,630	1,696
IPL [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	551	596	1,370	1,438
IPL [Member] | Electric [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	209	222	503	529
IPL [Member] | Electric [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	158	165	399	411
IPL [Member] | Electric [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	153	172	389	418
IPL [Member] | Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21	19	47	49
IPL [Member] | Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10	18	32	31
IPL [Member] | Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31	33	224	224
IPL [Member] | Gas [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	14	131	127
IPL [Member] | Gas [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9	8	65	62
IPL [Member] | Gas [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	3	8	10
IPL [Member] | Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6	8	20	25
IPL [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12	11	36	34
IPL [Member] | Other Utility [Member] | Steam [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11	9	32	29
IPL [Member] | Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	2	4	5
WPL [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	461	472	1,370	1,381
WPL [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	444	443	1,192	1,186
WPL [Member] | Electric [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	165	154	440	427
WPL [Member] | Electric [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	83	78	228	217
WPL [Member] | Electric [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	127	117	351	325
WPL [Member] | Electric [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38	49	107	119
WPL [Member] | Electric [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31	45	66	98
WPL [Member] | Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	16	29	176	194
WPL [Member] | Gas [Member] | Retail - residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9	14	102	110
WPL [Member] | Gas [Member] | Retail - commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	10	57	65
WPL [Member] | Gas [Member] | Retail - industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	1	4	5
WPL [Member] | Gas [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	4	13	14
WPL [Member] | Other Utility [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	0	2	1
WPL [Member] | Other Utility [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1	$ 0	$ 2	$ 1

XML

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2024	Dec. 31, 2023
Income Taxes [Line Items]
Regulatory assets			$ (40)	$ 102
Income tax expense (benefit)	$ 5	$ 14	3	26
Tax-related [Member]
Income Taxes [Line Items]
Regulatory assets	73
Income tax expense (benefit)	8	8
Forecast [Member]
Income Taxes [Line Items]
State income tax rate, percent					7.10%	8.40%
IPL [Member]
Income Taxes [Line Items]
Regulatory assets			(55)	(18)
Income tax expense (benefit)	(31)	(16)	(55)	(39)
IPL [Member] | Tax-related [Member]
Income Taxes [Line Items]
Regulatory assets	73
WPL [Member]
Income Taxes [Line Items]
Regulatory assets			16	120
Income tax expense (benefit)	$ 21	$ 16	$ 47	$ 50

XML

Income Taxes (Schedule Of Effective Income Tax Rates) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Effective Tax Rate [Line Items]
Overall income tax rate	2.00%	6.00%	1.00%	4.00%
IPL [Member]
Effective Tax Rate [Line Items]
Overall income tax rate	(22.00%)	(12.00%)	(20.00%)	(14.00%)
WPL [Member]
Effective Tax Rate [Line Items]
Overall income tax rate	16.00%	15.00%	15.00%	17.00%

XML

Income Taxes (Summary Of Tax Credit Carryforwards) (Details) $ in Millions	Sep. 30, 2023 USD ($)
State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	$ 431
Federal [Member]
Carryforwards [Line Items]
Tax credits, carryforward amount	737
IPL [Member] | State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	6
IPL [Member] | Federal [Member]
Carryforwards [Line Items]
Tax credits, carryforward amount	520
WPL [Member] | State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	1
WPL [Member] | Federal [Member]
Carryforwards [Line Items]
Tax credits, carryforward amount	$ 208

XML

Benefit Plans (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) shares
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost	$ 11
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost recognized over a weighted average period	1 year
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost recognized over a weighted average period	2 years
IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost	$ 6
WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation cost	$ 5
Omnibus Incentive Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Shares included in diluted earnings per share (in shares) | shares	274,960

XML

Benefit Plans (Defined Benefit Pension And Other Postretirement Benefits Plans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 3	$ 4	$ 7
Interest cost	12	9	35	27
Expected return on plan assets	(14)	(18)	(40)	(52)
Amortization of prior service credit	(1)	0	(1)	0
Amortization of actuarial loss	7	8	21	24
Total	6	2	19	6
OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	2	2
Interest cost	3	1	7	4
Expected return on plan assets	(2)	0	(4)	(3)
Amortization of prior service credit	0	0	0	0
Amortization of actuarial loss	0	1	1	2
Total	2	2	6	5
IPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	2	4
Interest cost	6	4	16	12
Expected return on plan assets	(6)	(7)	(19)	(23)
Amortization of actuarial loss	2	3	8	10
Total	2	1	7	3
IPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	1
Interest cost	1	1	3	2
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of actuarial loss	0	0	1	0
Total	0	0	1	0
WPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	2
Interest cost	5	4	15	12
Expected return on plan assets	(5)	(7)	(16)	(23)
Amortization of actuarial loss	3	4	10	12
Total	3	1	10	3
WPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	1	0
Interest cost	1	1	3	2
Expected return on plan assets	(1)	0	(1)	0
Amortization of actuarial loss	0	0	0	1
Total	$ 1	$ 1	$ 3	$ 3

XML

Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Compensation expense	$ 4	$ 3	$ 10	$ 9
Income tax benefits	1	1	3	3
IPL [Member]
Compensation expense	2	2	5	5
Income tax benefits	1	0	1	1
WPL [Member]
Compensation expense	2	1	4	4
Income tax benefits	$ 0	$ 0	$ 1	$ 1

XML

Benefit Plans (Summary Of Equity-based Compensation Plans Grants) (Details)	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants (in shares/units) | shares	108,513
Weighted average grant date fair value (in dollars per share/unit) | $ / shares	$ 55.68
Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants (in shares/units) | shares	123,990
Weighted average grant date fair value (in dollars per share/unit) | $ / shares	$ 52.71
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants (in shares/units) | shares	105,982
Weighted average grant date fair value (in dollars per share/unit) | $ / shares	$ 52.77

XML

Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Derivative Instruments [Line Items]
Non-current interest rate swap liabilities	$ 544		$ 544		$ 518
Accumulated other comprehensive income, interest rate swap	4		4		$ 0
Interest expense, interest rate swap	99	$ 83	289	$ 235
Alliant Energy Finance LLC [Member] | Interest Rate Swap [Member] | Term Loan Credit Agreement [Member]
Derivative Instruments [Line Items]
Interest rate swap	$ 300		$ 300
Interest rate swap, fixed interest rate percentage	3.93%		3.93%
Non-current interest rate swap liabilities	$ 6		$ 6
Accumulated other comprehensive income, interest rate swap	4		4
Interest expense, interest rate swap	$ 1		$ 2

XML

Derivative Instruments (Notional Amounts Of Derivative Instruments) (Details) - Commodity [Member]	9 Months Ended
	Sep. 30, 2023 Dekatherms MWh T
Electricity (MWhs) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	1,661
Electricity (MWhs) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	746
Electricity (MWhs) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	915
FTRs (MWhs) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	18,122
FTRs (MWhs) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	8,078
FTRs (MWhs) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in MWhs)	10,044
Natural Gas (Dths) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Dths) | Dekatherms	180,519
Natural Gas (Dths) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Dths) | Dekatherms	85,457
Natural Gas (Dths) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Dths) | Dekatherms	95,062
Coal (Tons) [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Tons) | T	370
Coal (Tons) [Member] | IPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Tons) | T	217
Coal (Tons) [Member] | WPL [Member]
Notional Amount of Derivatives [Line Items]
Notional unit amount of derivatives (in Tons) | T	153

XML

Derivative Instruments (Fair Value Of Financial Instruments) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Current derivative assets	$ 67	$ 111
Non-current derivative assets	62	126
Current derivative liabilities	32	59
Non-current derivative liabilities	34	20
IPL [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	51	69
Non-current derivative assets	34	69
Current derivative liabilities	15	40
Non-current derivative liabilities	6	6
WPL [Member]
Derivatives, Fair Value [Line Items]
Current derivative assets	16	42
Non-current derivative assets	28	57
Current derivative liabilities	17	19
Non-current derivative liabilities	$ 28	$ 14

XML

Derivative Instruments (Balance Sheet Offsetting) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	$ 129	$ 237
Derivative assets, Net	108	193
Derivative liabilities, Gross (as reported)	66	79
Derivative liabilities, Net	45	35
IPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	85	138
Derivative assets, Net	73	108
Derivative liabilities, Gross (as reported)	21	46
Derivative liabilities, Net	9	16
WPL [Member]
Derivative Instruments [Line Items]
Derivative assets, Gross (as reported)	44	99
Derivative assets, Net	35	85
Derivative liabilities, Gross (as reported)	45	33
Derivative liabilities, Net	$ 36	$ 19

XML

Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets:
Money market fund investments	$ 189	$ 10
Deferred proceeds	236	185
Liabilities:
Long-term debt (incl. current maturities)	7,863	7,339
IPL [Member]
Assets:
Money market fund investments	180	10
Deferred proceeds	236	185
Liabilities:
Long-term debt (incl. current maturities)	3,422	3,228
WPL [Member]
Assets:
Money market fund investments	9
Liabilities:
Long-term debt (incl. current maturities)	2,722	2,542
Commodity Contracts [Member]
Assets:
Derivatives	129	237
Liabilities:
Derivatives	66	79
Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	85	138
Liabilities:
Derivatives	21	46
Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	44	99
Liabilities:
Derivatives	45	33
Interest Rate Swap [Member]
Assets:
Derivatives	6	0
Level 1 [Member]
Assets:
Money market fund investments	189	10
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | IPL [Member]
Assets:
Money market fund investments	180	10
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 1 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Level 1 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	0	0
Level 2 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	7,863	7,338
Level 2 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	0	0
Liabilities:
Long-term debt (incl. current maturities)	3,422	3,228
Level 2 [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	2,722	2,542
Level 2 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	80	206
Liabilities:
Derivatives	60	67
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	45	111
Liabilities:
Derivatives	16	35
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	35	95
Liabilities:
Derivatives	44	32
Level 2 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	6	0
Level 3 [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	236	185
Liabilities:
Long-term debt (incl. current maturities)	0	1
Level 3 [Member] | IPL [Member]
Assets:
Money market fund investments	0	0
Deferred proceeds	236	185
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	0	0
Level 3 [Member] | Commodity Contracts [Member]
Assets:
Derivatives	49	31
Liabilities:
Derivatives	6	12
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	40	27
Liabilities:
Derivatives	5	11
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	9	4
Liabilities:
Derivatives	1	1
Level 3 [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	0	0
Carrying Amount [Member]
Assets:
Money market fund investments	189	10
Deferred proceeds	236	185
Liabilities:
Long-term debt (incl. current maturities)	8,838	8,076
Carrying Amount [Member] | IPL [Member]
Assets:
Money market fund investments	180	10
Deferred proceeds	236	185
Liabilities:
Long-term debt (incl. current maturities)	3,944	3,646
Carrying Amount [Member] | WPL [Member]
Liabilities:
Long-term debt (incl. current maturities)	3,069	2,770
Carrying Amount [Member] | Commodity Contracts [Member]
Assets:
Derivatives	129	237
Liabilities:
Derivatives	66	79
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member]
Assets:
Derivatives	85	138
Liabilities:
Derivatives	21	46
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member]
Assets:
Derivatives	44	99
Liabilities:
Derivatives	45	33
Carrying Amount [Member] | Interest Rate Swap [Member]
Assets:
Derivatives	$ 6	$ 0

XML

Fair Value Measurements (Fair Value Measurements Using Significant Unobservable Inputs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Commodity Contracts [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 54	$ 72	$ 19	$ 29
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	6	(17)
Purchases			62	79
Sales	(1)	0	(2)	0
Settlements	(27)	(26)	(42)	(46)
Ending balance	43	45	43	45
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	17	(1)	6	(17)
Commodity Contracts [Member] | IPL [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	41	58	16	18
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	0	(13)
Purchases			51	58
Sales	(1)	0	(2)	0
Settlements	(17)	(19)	(30)	(30)
Ending balance	35	33	35	33
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	12	(6)	0	(14)
Commodity Contracts [Member] | WPL [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	13	14	3	11
Total net gains (losses) included in changes in net assets (realized/unrealized)	5	5	6	(4)
Purchases			11	21
Settlements	(10)	(7)	(12)	(16)
Ending balance	8	12	8	12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	5	5	6	(3)
Deferred Proceeds [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	175	244	185	214
Total net gains (losses) included in changes in net assets (realized/unrealized)	0	0	0	0
Purchases			0	0
Sales	0	0	0	0
Settlements	61	4	51	34
Ending balance	236	248	236	248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	0	0	0	0
Deferred Proceeds [Member] | IPL [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	175	244	185	214
Total net gains (losses) included in changes in net assets (realized/unrealized)	0	0	0	0
Purchases			0	0
Sales	0	0	0	0
Settlements	61	4	51	34
Ending balance	236	248	236	248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$ 0	$ 0	$ 0	$ 0

XML

Fair Value Measurements (Fair Value Of Net Derivative Assets (Liabilities)) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	$ 43	$ 54	$ 19	$ 45	$ 72	$ 29
Excluding Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	3
Fair value, net derivative liabilities			(10)
Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	40		29
IPL [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	35	41	16	33	58	18
IPL [Member] | Excluding Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	4
Fair value, net derivative liabilities			(9)
IPL [Member] | Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	31		25
WPL [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	8	$ 13	3	$ 12	$ 14	$ 11
WPL [Member] | Excluding Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative liabilities	(1)		(1)
WPL [Member] | Financial Transmission Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, net derivative assets	$ 9		$ 4

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Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 1,275
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	596
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	631
Capital Purchase Commitment [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	221
Capital Purchase Commitment [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	175
Capital Purchase Commitment [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	46
Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum	51
Indemnification Agreement [Member] | Purchased Power [Member]
Commitments and Contingencies [Line Items]
Obligations, maximum	$ 17
Whiting Petroleum Affiliate [Member]
Commitments and Contingencies [Line Items]
Partnership share, percent	6.00%
Obligations, maximum	$ 58
Credit loss liability	$ 5
Federal Energy Regulatory Commission [Member]
Commitments and Contingencies [Line Items]
MISO base return on equity, percentage		10.02%	9.88%

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Commitments And Contingencies (Other Purchase Commitments) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 1,275
Individual commitments incurred	1
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	596
Individual commitments incurred	1
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	631
Individual commitments incurred	1
Natural gas [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	962
Natural gas [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	436
Natural gas [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	526
Coal [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	188
Coal [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	108
Coal [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	80
Other [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	125
Other [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	52
Other [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 25

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Commitments And Contingencies (MPG Site Estimated Future Costs And Recorded Liabilities) (Details) - Natural Gas Processing Plant [Member] $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Commitments and Contingencies [Line Items]
Current and non-current environmental liabilities	$ 18
IPL [Member]
Commitments and Contingencies [Line Items]
Current and non-current environmental liabilities	8
WPL [Member]
Commitments and Contingencies [Line Items]
Current and non-current environmental liabilities	10
Minimum [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	9
Minimum [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	5
Minimum [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	4
Maximum [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	36
Maximum [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	11
Maximum [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Range of estimated future costs	$ 25

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Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Revenues	$ 1,077	$ 1,135	$ 3,066	$ 3,147
Operating income (loss)	322	309	760	769
Net income (loss) attributable to common shareowners	259	227	582	579
Net income			582	579
IPL [Member]
Segment Reporting Information [Line Items]
Revenues	594	640	1,630	1,696
Operating income (loss)	173	171	379	389
Net income	170	154	331	327
WPL [Member]
Segment Reporting Information [Line Items]
Revenues	461	472	1,370	1,381
Operating income (loss)	142	131	363	357
Net income	107	91	267	247
Electric [Member]
Segment Reporting Information [Line Items]
Revenues	995	1,039	2,562	2,624
Operating income (loss)	319	304	682	680
Electric [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	551	596	1,370	1,438
Operating income (loss)	171	174	342	353
Electric [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	444	443	1,192	1,186
Operating income (loss)	148	130	340	327
Gas [Member]
Segment Reporting Information [Line Items]
Revenues	47	62	400	418
Operating income (loss)	(4)	(3)	48	62
Gas [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	31	33	224	224
Operating income (loss)	(2)	(3)	25	33
Gas [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	16	29	176	194
Operating income (loss)	(2)	0	23	29
Other Utility [Member]
Segment Reporting Information [Line Items]
Revenues	13	11	38	35
Operating income (loss)	0	1	12	4
Other Utility [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	12	11	36	34
Operating income (loss)	4	0	12	3
Other Utility [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	1	0	2	1
Operating income (loss)	(4)	1	0	1
Non-utility and Other [Member]
Segment Reporting Information [Line Items]
Revenues	22	23	66	70
Operating income (loss)	7	7	18	23
Net income (loss) attributable to common shareowners	(18)	(18)	(16)	5
Utility Business [Member]
Segment Reporting Information [Line Items]
Revenues	1,055	1,112	3,000	3,077
Operating income (loss)	315	302	742	746
Net income (loss) attributable to common shareowners	$ 277	$ 245	$ 598	$ 574

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Related Parties (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
WPL [Member] | WPL Owed ATC LLC [Member] | Related Party [Member]
Related Party Transactions [Line Items]
Net amounts owed	$ 9	$ 10

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Related Parties (Service Agreements) (Details) - Corporate Services [Member] - Subsidiary of Common Parent [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Corporate Services Billings [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 46	$ 45	$ 134	$ 136
Corporate Services Billings [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	40	39	120	117
Sales Credited [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	3	11	11	11
Sales Credited [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	23	31	45	62
Purchases Billed [Member] | IPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	133	119	320	342
Purchases Billed [Member] | WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 5	$ 42	$ 21	$ 103

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Related Parties (Net Intercompany Payables) (Details) - Related Party [Member] - Corporate Services [Member] - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
IPL [Member]
Related Party Transactions [Line Items]
Net amounts owed	$ 136	$ 103
WPL [Member]
Related Party Transactions [Line Items]
Net amounts owed	$ 71	$ 56

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Related Parties (Amounts Billed Between Parties) (Details) - ATC LLC [Member] - WPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
ATC Billings To WPL [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 41	$ 38	$ 119	$ 107
WPL Billings To ATC [Member]
Related Party Transactions [Line Items]
Amounts billed between related parties	$ 5	$ 6	$ 16	$ 14