Summary Of Significant Accounting Policies

9 Months Ended

Sep. 30, 2012

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(a) General - The interim condensed consolidated financial statements included herein have been prepared by Alliant Energy, IPL and WPL, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the U.S. (GAAP) have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. Alliant Energy’s condensed consolidated financial statements include the accounts of Alliant Energy and its consolidated subsidiaries (including IPL, WPL, Resources and Alliant Energy Corporate Services, Inc. (Corporate Services)). IPL’s condensed consolidated financial statements include the accounts of IPL and its consolidated subsidiary. WPL’s condensed consolidated financial statements include the accounts of WPL and its consolidated subsidiaries. These financial statements should be read in conjunction with the financial statements and the notes thereto included in Alliant Energy’s, IPL’s and WPL’s latest combined Annual Report on 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 condensed consolidated results of operations for the three and nine months ended September 30, 2012 and 2011, the condensed consolidated financial position at September 30, 2012 and December 31, 2011, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2012 and 2011 have been made. Results for the nine months ended September 30, 2012 are not necessarily indicative of results that may be expected for the year ending December 31, 2012. A change in management’s estimates or assumptions could have a material impact on Alliant Energy’s, IPL’s and WPL’s respective financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Condensed Consolidated Financial Statements and Notes to Condensed Consolidated Financial Statements have been reclassified to conform to the current period presentation for comparative purposes. Unless otherwise noted, the notes herein have been revised to exclude discontinued operations and assets and liabilities held for sale for all periods presented.

(b) Regulatory Assets and Regulatory Liabilities -

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



	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Tax-related		$709.4		$634.7		$686.2		$614.6		$23.2		$20.1
Pension and other postretirement benefits costs	495.4		514.1		256.3		264.9		239.1		249.2
Asset retirement obligations (AROs)	57.8		65.9		38.7		48.7		19.1		17.2
Derivatives	56.6		77.7		22.6		33.5		34.0		44.2
Environmental-related costs	36.3		38.9		31.5		32.2		4.8		6.7
Emission allowances	30.0		30.0		30.0		30.0		—		—
Debt redemption costs	20.3		21.8		14.0		15.1		6.3		6.7
IPL’s electric transmission service costs	18.7		24.9		18.7		24.9		—		—
Proposed base-load projects costs	16.0		21.5		11.4		15.3		4.6		6.2
Other	77.9		65.5		41.6		38.1		36.3		27.4
		$1,518.4		$1,495.0		$1,151.0		$1,117.3		$367.4		$377.7

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



	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Cost of removal obligations		$406.6		$404.9		$266.5		$261.9		$140.1		$143.0
IPL’s tax benefit rider	327.4		349.6		327.4		349.6		—		—
Energy conservation cost recovery	48.8		29.6		8.9		4.7		39.9		24.9
IPL’s electric transmission assets sale	35.2		45.1		35.2		45.1		—		—
Derivatives	21.3		7.2		10.2		3.6		11.1		3.6
Commodity cost recovery	20.4		23.8		14.8		23.2		5.6		0.6
Other	46.7		49.9		25.1		33.2		21.6		16.7
		$906.4		$910.1		$688.1		$721.3		$218.3		$188.8

Tax-related - Alliant Energy’s and IPL’s tax-related regulatory assets are generally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles. Deferred tax amounts are recorded to regulatory assets, along with the necessary revenue requirement tax gross-ups. During the nine months ended September 30, 2012, Alliant Energy’s and IPL’s tax-related regulatory assets increased primarily due to changes in the estimated amount of qualifying repair expenditures and allocation of mixed service costs at IPL.

Derivatives - In accordance with IPL’s and WPL’s fuel and natural gas recovery mechanisms, prudently incurred costs from derivative instruments are recovered from customers in the future after any losses are realized and gains from derivative instruments are refunded to customers in the future after any gains are realized. Based on these recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on Alliant Energy’s, IPL’s and WPL’s Condensed Consolidated Balance Sheets for the nine months ended September 30, 2012. Refer to Note 10 for additional details of Alliant Energy’s, IPL’s and WPL’s derivative assets and derivative liabilities.

Emission allowances - IPL entered into forward contracts in 2007 to purchase sulfur dioxide (SO2) emission allowances with vintage years of 2014 through 2017 from various counterparties for $34 million to meet future Clean Air Interstate Rule (CAIR) emission reduction standards. Any SO2 emission allowances acquired under these forward contracts may be used to meet requirements under the existing Acid Rain program regulations or the more stringent CAIR emission reduction standards but are not eligible to be used for compliance requirements under the Cross-State Air Pollution Rule (CSAPR). In July 2011, the EPA issued CSAPR to replace CAIR with an anticipated effective date in 2012. As a result of the issuance of CSAPR, Alliant Energy and IPL concluded in the third quarter of 2011 that the allowances to be acquired under these forward contracts would not be needed by IPL to comply with expected environmental regulations in the future. The value of these allowances was nominal, which was significantly below the $34 million contract price for these allowances. As a result, Alliant Energy and IPL recognized charges of $34 million for these forward contracts in the third quarter of 2011. The $34 million obligation was recorded in other long-term liabilities and deferred credits in the third quarter of 2011. Alliant Energy and IPL concluded that $30 million of the charges are probable of recovery from IPL’s customers and therefore were recorded to regulatory assets in the third quarter of 2011. The remaining $4 million of charges were determined not to be probable of recovery from IPL’s customers resulting in $2 million of charges related to electric customers recorded to “Electric production fuel and energy purchases” and $2 million of charges related to steam customers recorded to “Utility - Other operation and maintenance” in Alliant Energy’s and IPL’s Condensed Consolidated Statements of Income for the three and nine months ended September 30, 2011. In August 2012, the U.S. Court of Appeals for the D.C. Circuit (D.C. Circuit Court) issued its opinion to the EPA vacating and remanding CSAPR for further revision to the EPA. The D.C. Circuit Court order also requires the EPA to continue administering CAIR pending the promulgation of a valid replacement for CSAPR. Despite CSAPR being vacated, the current value of these allowances continues to be nominal and significantly below the $34 million contract price for these allowances. Alliant Energy and IPL currently believe that CAIR will be replaced in the future, either by a modified CSAPR or another rule that addresses the interstate transport of air pollutants.

Proposed base-load projects costs - In accordance with the Minnesota Public Utilities Commission’s (MPUC’s) August 2011 order related to IPL’s 2009 test year Minnesota retail electric rate case, IPL was authorized to recover $2 million of previously incurred plant cancellation costs for its proposed base-load project referred to as Sutherland #4. As a result, Alliant Energy and IPL recorded a $2 million increase to regulatory assets, and a $2 million credit to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income for the nine months ended September 30, 2011.

IPL’s tax benefit rider - Alliant Energy’s and IPL’s “IPL’s tax benefit rider” regulatory liabilities in the above table decreased $22 million primarily due to $63 million of regulatory liabilities used to credit IPL’s Iowa retail electric customers’ bills during the nine months ended September 30, 2012. This item was offset by changes in the estimated amounts of qualifying repair expenditures and allocation of mixed service costs at IPL. Refer to Note 2 for discussion of a proposed tax benefit rider for IPL’s Iowa retail gas customers and Note 4 for additional details regarding the tax benefit rider for IPL’s Iowa retail electric customers.

Energy conservation cost recovery - WPL collects revenues from its customers to offset certain expenditures incurred by WPL for conservation programs, including state mandated programs and WPL’s Shared Savings program. Differences between forecasted costs used to set rates and actual costs for these programs are deferred as a regulatory asset or regulatory liability. During the nine months ended September 30, 2012, WPL’s forecasted costs used to set current rates exceeded actual costs for these programs, resulting in a $15 million increase to Alliant Energy’s and WPL’s “Energy conservation cost recovery” regulatory liability.

IPL’s electric transmission assets sale - In accordance with the MPUC’s August 2011 order related to IPL’s 2009 test year Minnesota retail electric rate case, IPL was authorized to refund a higher amount of the gain realized from the sale of its electric transmission assets in 2007 to its Minnesota retail electric customers than previously estimated. As a result, Alliant Energy and IPL recorded a $5 million increase to regulatory liabilities, and a $5 million charge to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income for the nine months ended September 30, 2011 for the additional amount to be refunded.

Other - Based on an assessment completed for the nine months ended September 30, 2011, Alliant Energy, IPL and WPL recognized impairment charges of $7 million, $2 million and $5 million, respectively, for regulatory assets that were no longer probable of future recovery. The regulatory asset impairment charges were recorded by Alliant Energy, IPL and WPL as reductions in regulatory assets, and charges to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income for the nine months ended September 30, 2011.

Based on the Public Service Commission of Wisconsin’s (PSCW’s) July 2012 order related to WPL’s 2013/2014 test period Wisconsin retail electric and gas rate case, WPL was authorized to recover previously incurred costs associated with the acquisition of a 25% ownership interest in Edgewater Unit 5 and proposed clean air compliance plan projects. As a result, Alliant Energy and WPL recorded a $5 million increase to “Regulatory assets” on their Condensed Consolidated Balance Sheets and a $5 million credit to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income for the nine months ended September 30, 2012.

WPL’s Edgewater Unit 5 Emission Controls Project - WPL is currently installing a selective catalytic reduction (SCR) system at Edgewater Unit 5 to reduce nitrogen oxide (NOx) emissions at the generating facility. Construction began in the third quarter of 2010 and is expected to be completed by the end of 2012. The SCR is expected to help meet requirements under the Wisconsin Reasonably Available Control Technology (RACT) Rule, which require additional NOx emission reductions at Edgewater by May 2013. As of September 30, 2012, WPL recorded capitalized expenditures of $116 million and allowance for funds used during construction (AFUDC) of $8 million for the SCR system in “Construction work in progress - Edgewater Generating Station Unit 5 emission controls” on Alliant Energy’s and WPL’s Condensed Consolidated Balance Sheets.

WPL’s Columbia Units 1 and 2 Emission Controls Project - WPL is currently installing scrubbers and baghouses at Columbia Units 1 and 2 to reduce SO2 and mercury emissions at the generating facility. WPL owns a 46.2% interest in Columbia Units 1 and 2. Construction began in the first quarter of 2012 and is expected to be completed in 2014. The scrubbers and baghouses are expected to help meet requirements under CAIR or some alternative to this rule that may be implemented, the Utility Maximum Achievable Control Technology (MACT) Rule and the Wisconsin State Mercury Rule. As of September 30, 2012, WPL recorded capitalized expenditures of $90 million and AFUDC of $2 million for its allocated portion of the scrubbers and baghouses in “Construction work in progress - Columbia Energy Center Units 1 and 2 emission controls” on Alliant Energy’s and WPL’s Condensed Consolidated Balance Sheets.

IPL’s George Neal Units 3 and 4 Emission Controls Project - MidAmerican Energy Company (MidAmerican) is currently installing scrubbers and baghouses at George Neal Units 3 and 4 to reduce SO2 and mercury emissions at the generating facility. IPL owns a 28.0% and 25.695% interest in George Neal Units 3 and 4, respectively. Construction began in the fourth quarter of 2011 and is expected to be completed in 2013 and 2014. The scrubbers and baghouses are expected to help meet requirements under CAIR or some alternative to this rule that may be implemented and the Utility MACT Rule. As of September 30, 2012, IPL recorded capitalized expenditures of $53 million and AFUDC of $1 million for its allocated portion of the scrubbers and baghouses in “Construction work in progress - George Neal Generating Station Units 3 and 4 emission controls” on Alliant Energy’s and IPL’s Condensed Consolidated Balance Sheets.

IPL’s Ottumwa Unit 1 Emission Controls Project - IPL is currently installing a scrubber and baghouse at Ottumwa Unit 1 to reduce SO2 and mercury emissions at the generating facility. IPL owns a 48% interest in Ottumwa Unit 1. Construction began in the second quarter of 2012 and is expected to be completed in 2014. The scrubber and baghouse are expected to help meet requirements under CAIR or some alternative to this rule that may be implemented and the Utility MACT Rule. As of September 30, 2012, IPL recorded capitalized expenditures of $52 million and AFUDC of $1 million for its allocated portion of the scrubber and baghouse in “Construction work in progress - Ottumwa Generating Station Unit 1 emission controls” on Alliant Energy’s and IPL’s Condensed Consolidated Balance Sheets.

Franklin County Wind Project - In 2008, Alliant Energy entered into a master supply agreement with Vestas-American Wind Technology, Inc. (Vestas) to purchase 500 MW of wind turbine generator sets and related equipment. Alliant Energy utilized 400 MW of these wind turbine generator sets and related equipment to construct IPL’s Whispering Willow - East and WPL’s Bent Tree - Phase I wind projects. In the second quarter of 2011, Alliant Energy decided to utilize the remaining 100 MW of wind turbine generator sets and related equipment at Resources to build the Franklin County wind project. In the second quarter of 2011, IPL sold the assets for this wind project to Resources for $115.3 million, which represented IPL’s book value for progress payments to date for the 100 MW of wind turbine generator sets and related equipment and land rights in Franklin County, Iowa. In addition, Resources assumed the remaining progress payments to Vestas for the 100 MW of wind turbine generator sets and related equipment. The proceeds received by IPL were recorded in investing activities in IPL’s Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2011. Refer to Note 1(d) for further discussion of the Franklin County wind project.

IPL’s Whispering Willow - East Wind Project - In 2011, IPL received an order from the MPUC approving a temporary recovery rate for the Minnesota retail portion of its Whispering Willow - East wind project construction costs. In its order, the MPUC did not conclude on the prudence of these project costs. The prudence of these project costs and the final recovery rate for these costs will be addressed in a separate proceeding that is expected to be completed in 2013. The initial recovery rate approved by the MPUC is below the amount required by IPL to recover the Minnesota retail portion of its total project costs. Based on its interpretation of the order, IPL currently believes that it is probable it will not be allowed to recover the entire Minnesota retail portion of its project costs. IPL currently believes the most likely outcome of the final rate proceeding will result in the MPUC effectively disallowing recovery of approximately $8 million of project costs out of a total of approximately $30 million of project costs allocated to the Minnesota retail jurisdiction. As a result, IPL recognized an $8 million impairment related to this probable disallowance, which was recorded as a reduction to electric plant in service and a charge to “Utility - Other operation and maintenance” in Alliant Energy’s and IPL’s Condensed Consolidated Statements of Income for the nine months ended September 30, 2011. This amount is subject to change until the MPUC determines the final recovery rate for these project costs.

Wind Site in Green Lake and Fond du Lac Counties in Wisconsin - In 2009, WPL purchased development rights to an approximate 100 MW wind site in Green Lake and Fond du Lac Counties in Wisconsin. Due to events in the first quarter of 2011 resulting in uncertainty regarding wind siting requirements in Wisconsin and increased risks with permitting this wind site, WPL determined it would be difficult to sell or effectively use the site for wind development. As a result, WPL recognized a $5 million impairment in the first quarter of 2011 for the amount of capitalized costs incurred for this site. The impairment was recorded as a reduction in other utility property, plant and equipment, and a charge to “Utility - Other operation and maintenance” in Alliant Energy’s and WPL’s Condensed Consolidated Statements of Income for the nine months ended September 30, 2011.

Depreciation - In May 2012, the PSCW issued an order approving the implementation of updated depreciation rates for WPL as a result of a recently completed depreciation study. The updated depreciation rates will be effective January 1, 2013 for all assets other than Riverside. WPL’s depreciation rates for Riverside will be effective on the purchase date of Riverside. WPL estimates the new average rates of depreciation for its electric generation, electric distribution and gas properties will be approximately 3.4%, 2.7% and 2.5%, respectively, during 2013.

(d) Non-regulated and Other Property, Plant and Equipment - As of September 30, 2012, Alliant Energy recorded capitalized expenditures of $198 million, capitalized interest of $8 million and AROs of $8 million in Non-regulated Generation property, plant and equipment on Alliant Energy’s balance sheet related to Resources’ Franklin County wind project. Alliant Energy expects to place the Franklin County wind project in service in the fourth quarter of 2012. Refer to Note 1(c) for further discussion of the Franklin County wind project and Note 14 for further discussion of the Franklin County wind project AROs.

In April 2012, Alliant Energy exercised its option under the corporate headquarters lease and purchased the building at the expiration of the lease term for $48 million.

(e) Comprehensive Income - For the three and nine months ended September 30, 2012 and 2011, Alliant Energy’s other comprehensive income was not material; therefore, its comprehensive income was substantially equal to its net income for such periods. For the three and nine months ended September 30, 2012 and 2011, IPL and WPL had no other comprehensive income; therefore their comprehensive income was equal to their earnings available for common stock for such periods.

(f) Cash Flows Presentation - Alliant Energy reports cash flows from continuing operations together with cash flows from discontinued operations in its Condensed Consolidated Statements of Cash Flows. Refer to Note 13 for details of cash flows from discontinued operations.

IPL [Member]

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(b) Regulatory Assets and Regulatory Liabilities -

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



	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Tax-related		$709.4		$634.7		$686.2		$614.6		$23.2		$20.1
Pension and other postretirement benefits costs	495.4		514.1		256.3		264.9		239.1		249.2
Asset retirement obligations (AROs)	57.8		65.9		38.7		48.7		19.1		17.2
Derivatives	56.6		77.7		22.6		33.5		34.0		44.2
Environmental-related costs	36.3		38.9		31.5		32.2		4.8		6.7
Emission allowances	30.0		30.0		30.0		30.0		—		—
Debt redemption costs	20.3		21.8		14.0		15.1		6.3		6.7
IPL’s electric transmission service costs	18.7		24.9		18.7		24.9		—		—
Proposed base-load projects costs	16.0		21.5		11.4		15.3		4.6		6.2
Other	77.9		65.5		41.6		38.1		36.3		27.4
		$1,518.4		$1,495.0		$1,151.0		$1,117.3		$367.4		$377.7

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



	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Cost of removal obligations		$406.6		$404.9		$266.5		$261.9		$140.1		$143.0
IPL’s tax benefit rider	327.4		349.6		327.4		349.6		—		—
Energy conservation cost recovery	48.8		29.6		8.9		4.7		39.9		24.9
IPL’s electric transmission assets sale	35.2		45.1		35.2		45.1		—		—
Derivatives	21.3		7.2		10.2		3.6		11.1		3.6
Commodity cost recovery	20.4		23.8		14.8		23.2		5.6		0.6
Other	46.7		49.9		25.1		33.2		21.6		16.7
		$906.4		$910.1		$688.1		$721.3		$218.3		$188.8

In April 2012, Alliant Energy exercised its option under the corporate headquarters lease and purchased the building at the expiration of the lease term for $48 million.

WPL [Member]

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(b) Regulatory Assets and Regulatory Liabilities -

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



	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Tax-related		$709.4		$634.7		$686.2		$614.6		$23.2		$20.1
Pension and other postretirement benefits costs	495.4		514.1		256.3		264.9		239.1		249.2
Asset retirement obligations (AROs)	57.8		65.9		38.7		48.7		19.1		17.2
Derivatives	56.6		77.7		22.6		33.5		34.0		44.2
Environmental-related costs	36.3		38.9		31.5		32.2		4.8		6.7
Emission allowances	30.0		30.0		30.0		30.0		—		—
Debt redemption costs	20.3		21.8		14.0		15.1		6.3		6.7
IPL’s electric transmission service costs	18.7		24.9		18.7		24.9		—		—
Proposed base-load projects costs	16.0		21.5		11.4		15.3		4.6		6.2
Other	77.9		65.5		41.6		38.1		36.3		27.4
		$1,518.4		$1,495.0		$1,151.0		$1,117.3		$367.4		$377.7

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



	Alliant Energy				IPL				WPL
	September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011		September 30, 2012		December 31, 2011
Cost of removal obligations		$406.6		$404.9		$266.5		$261.9		$140.1		$143.0
IPL’s tax benefit rider	327.4		349.6		327.4		349.6		—		—
Energy conservation cost recovery	48.8		29.6		8.9		4.7		39.9		24.9
IPL’s electric transmission assets sale	35.2		45.1		35.2		45.1		—		—
Derivatives	21.3		7.2		10.2		3.6		11.1		3.6
Commodity cost recovery	20.4		23.8		14.8		23.2		5.6		0.6
Other	46.7		49.9		25.1		33.2		21.6		16.7
		$906.4		$910.1		$688.1		$721.3		$218.3		$188.8

In April 2012, Alliant Energy exercised its option under the corporate headquarters lease and purchased the building at the expiration of the lease term for $48 million.

- Definition

The entire disclosure for all significant accounting policies of the reporting entity.

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