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.