Summary Of Significant Accounting Policies

6 Months Ended

Jun. 30, 2013

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(a) General - The interim unaudited condensed consolidated financial statements included herein have been prepared by Alliant Energy, IPL and WPL 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 subsidiary. 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 six months ended June 30, 2013 and 2012, the condensed consolidated financial position at June 30, 2013 and December 31, 2012, and the condensed consolidated statements of cash flows for the six months ended June 30, 2013 and 2012 have been made. Results for the six months ended June 30, 2013 are not necessarily indicative of results that may be expected for the year ending December 31, 2013. 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 Combined 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
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
Tax-related		$793.1		$770.7		$768.2		$746.2		$24.9		$24.5
Pension and other postretirement benefits costs	533.2		549.2		271.7		279.3		261.5		269.9
Asset retirement obligations (AROs)	66.6		62.4		39.2		38.6		27.4		23.8
Derivatives	37.1		40.2		10.0		16.3		27.1		23.9
Environmental-related costs	31.5		34.9		27.2		30.3		4.3		4.6
Emission allowances	30.0		30.0		30.0		30.0		—		—
Other	120.6		125.0		77.9		77.2		42.7		47.8
		$1,612.1		$1,612.4		$1,224.2		$1,217.9		$387.9		$394.5

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

	Alliant Energy				IPL				WPL
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
Cost of removal obligations		$412.8		$408.7		$273.1		$268.0		$139.7		$140.7
IPL’s tax benefit riders	313.0		355.8		313.0		355.8		—		—
Energy conservation cost recovery	62.1		55.1		16.7		10.0		45.4		45.1
IPL’s electric transmission assets sale	27.1		32.5		27.1		32.5		—		—
Commodity cost recovery	25.0		17.7		7.4		5.2		17.6		12.5
Other	58.1		46.3		35.1		29.9		23.0		16.4
		$898.1		$916.1		$672.4		$701.4		$225.7		$214.7

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 six months ended June 30, 2013, Alliant Energy’s and IPL’s tax-related regulatory assets increased primarily due to qualifying repair expenditures at IPL.

IPL’s tax benefit riders - Alliant Energy’s and IPL’s “IPL’s tax benefit riders” regulatory liabilities in the above table decreased $43 million during the six months ended June 30, 2013 due to the following items:

Electric tax benefit rider - In January 2011, the Iowa Utilities Board (IUB) approved an electric tax benefit rider proposed by IPL, which utilizes regulatory liabilities to credit bills of Iowa retail electric customers beginning in February 2011 to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures, allocation of mixed service costs and allocation of insurance proceeds from floods in 2008. IPL utilized $38 million of regulatory liabilities to credit Iowa retail electric customers’ bills during the six months ended June 30, 2013.

Gas tax benefit rider - In November 2012, the IUB approved a gas tax benefit rider proposed by IPL, which utilizes regulatory liabilities to credit bills of Iowa retail gas customers beginning in January 2013 to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures, allocation of mixed service costs and allocation of insurance proceeds from floods in 2008. IPL utilized $5 million of regulatory liabilities to credit Iowa retail gas customers’ bills during the six months ended June 30, 2013.

Refer to Note 4 for additional details regarding IPL’s tax benefit riders.

Other - 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, and a $5 million credit to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income in the second quarter of 2012.

(c) Comprehensive Income - For the three and six months ended June 30, 2013 and 2012, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income and its comprehensive income attributable to Alliant Energy common shareowners was equal to its net income attributable to Alliant Energy common shareowners for such periods. For the three and six months ended June 30, 2013 and 2012, IPL and WPL had no other comprehensive income; therefore, their comprehensive income was equal to their net income and their comprehensive income available for common stock was equal to their earnings available for common stock for such periods.

IPL [Member]

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(a) General - The interim unaudited condensed consolidated financial statements included herein have been prepared by Alliant Energy, IPL and WPL 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 subsidiary. 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 six months ended June 30, 2013 and 2012, the condensed consolidated financial position at June 30, 2013 and December 31, 2012, and the condensed consolidated statements of cash flows for the six months ended June 30, 2013 and 2012 have been made. Results for the six months ended June 30, 2013 are not necessarily indicative of results that may be expected for the year ending December 31, 2013. 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 Combined 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
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
Tax-related		$793.1		$770.7		$768.2		$746.2		$24.9		$24.5
Pension and other postretirement benefits costs	533.2		549.2		271.7		279.3		261.5		269.9
Asset retirement obligations (AROs)	66.6		62.4		39.2		38.6		27.4		23.8
Derivatives	37.1		40.2		10.0		16.3		27.1		23.9
Environmental-related costs	31.5		34.9		27.2		30.3		4.3		4.6
Emission allowances	30.0		30.0		30.0		30.0		—		—
Other	120.6		125.0		77.9		77.2		42.7		47.8
		$1,612.1		$1,612.4		$1,224.2		$1,217.9		$387.9		$394.5

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

	Alliant Energy				IPL				WPL
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
Cost of removal obligations		$412.8		$408.7		$273.1		$268.0		$139.7		$140.7
IPL’s tax benefit riders	313.0		355.8		313.0		355.8		—		—
Energy conservation cost recovery	62.1		55.1		16.7		10.0		45.4		45.1
IPL’s electric transmission assets sale	27.1		32.5		27.1		32.5		—		—
Commodity cost recovery	25.0		17.7		7.4		5.2		17.6		12.5
Other	58.1		46.3		35.1		29.9		23.0		16.4
		$898.1		$916.1		$672.4		$701.4		$225.7		$214.7

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 six months ended June 30, 2013, Alliant Energy’s and IPL’s tax-related regulatory assets increased primarily due to qualifying repair expenditures at IPL.

IPL’s tax benefit riders - Alliant Energy’s and IPL’s “IPL’s tax benefit riders” regulatory liabilities in the above table decreased $43 million during the six months ended June 30, 2013 due to the following items:

Electric tax benefit rider - In January 2011, the Iowa Utilities Board (IUB) approved an electric tax benefit rider proposed by IPL, which utilizes regulatory liabilities to credit bills of Iowa retail electric customers beginning in February 2011 to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures, allocation of mixed service costs and allocation of insurance proceeds from floods in 2008. IPL utilized $38 million of regulatory liabilities to credit Iowa retail electric customers’ bills during the six months ended June 30, 2013.

Gas tax benefit rider - In November 2012, the IUB approved a gas tax benefit rider proposed by IPL, which utilizes regulatory liabilities to credit bills of Iowa retail gas customers beginning in January 2013 to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures, allocation of mixed service costs and allocation of insurance proceeds from floods in 2008. IPL utilized $5 million of regulatory liabilities to credit Iowa retail gas customers’ bills during the six months ended June 30, 2013.

Refer to Note 4 for additional details regarding IPL’s tax benefit riders.

Other - 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, and a $5 million credit to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income in the second quarter of 2012.

(c) Comprehensive Income - For the three and six months ended June 30, 2013 and 2012, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income and its comprehensive income attributable to Alliant Energy common shareowners was equal to its net income attributable to Alliant Energy common shareowners for such periods. For the three and six months ended June 30, 2013 and 2012, IPL and WPL had no other comprehensive income; therefore, their comprehensive income was equal to their net income and their comprehensive income available for common stock was equal to their earnings available for common stock for such periods.

WPL [Member]

Summary Of Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(a) General - The interim unaudited condensed consolidated financial statements included herein have been prepared by Alliant Energy, IPL and WPL 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 subsidiary. 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 six months ended June 30, 2013 and 2012, the condensed consolidated financial position at June 30, 2013 and December 31, 2012, and the condensed consolidated statements of cash flows for the six months ended June 30, 2013 and 2012 have been made. Results for the six months ended June 30, 2013 are not necessarily indicative of results that may be expected for the year ending December 31, 2013. 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 Combined 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
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
Tax-related		$793.1		$770.7		$768.2		$746.2		$24.9		$24.5
Pension and other postretirement benefits costs	533.2		549.2		271.7		279.3		261.5		269.9
Asset retirement obligations (AROs)	66.6		62.4		39.2		38.6		27.4		23.8
Derivatives	37.1		40.2		10.0		16.3		27.1		23.9
Environmental-related costs	31.5		34.9		27.2		30.3		4.3		4.6
Emission allowances	30.0		30.0		30.0		30.0		—		—
Other	120.6		125.0		77.9		77.2		42.7		47.8
		$1,612.1		$1,612.4		$1,224.2		$1,217.9		$387.9		$394.5

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

	Alliant Energy				IPL				WPL
	June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012		June 30, 2013		December 31, 2012
Cost of removal obligations		$412.8		$408.7		$273.1		$268.0		$139.7		$140.7
IPL’s tax benefit riders	313.0		355.8		313.0		355.8		—		—
Energy conservation cost recovery	62.1		55.1		16.7		10.0		45.4		45.1
IPL’s electric transmission assets sale	27.1		32.5		27.1		32.5		—		—
Commodity cost recovery	25.0		17.7		7.4		5.2		17.6		12.5
Other	58.1		46.3		35.1		29.9		23.0		16.4
		$898.1		$916.1		$672.4		$701.4		$225.7		$214.7

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 six months ended June 30, 2013, Alliant Energy’s and IPL’s tax-related regulatory assets increased primarily due to qualifying repair expenditures at IPL.

IPL’s tax benefit riders - Alliant Energy’s and IPL’s “IPL’s tax benefit riders” regulatory liabilities in the above table decreased $43 million during the six months ended June 30, 2013 due to the following items:

Electric tax benefit rider - In January 2011, the Iowa Utilities Board (IUB) approved an electric tax benefit rider proposed by IPL, which utilizes regulatory liabilities to credit bills of Iowa retail electric customers beginning in February 2011 to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures, allocation of mixed service costs and allocation of insurance proceeds from floods in 2008. IPL utilized $38 million of regulatory liabilities to credit Iowa retail electric customers’ bills during the six months ended June 30, 2013.

Gas tax benefit rider - In November 2012, the IUB approved a gas tax benefit rider proposed by IPL, which utilizes regulatory liabilities to credit bills of Iowa retail gas customers beginning in January 2013 to help offset the impact of rate increases on such customers. These regulatory liabilities are related to tax benefits from tax accounting method changes for repairs expenditures, allocation of mixed service costs and allocation of insurance proceeds from floods in 2008. IPL utilized $5 million of regulatory liabilities to credit Iowa retail gas customers’ bills during the six months ended June 30, 2013.

Refer to Note 4 for additional details regarding IPL’s tax benefit riders.

Other - 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, and a $5 million credit to “Utility - Other operation and maintenance” in their Condensed Consolidated Statements of Income in the second quarter of 2012.

(c) Comprehensive Income - For the three and six months ended June 30, 2013 and 2012, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income and its comprehensive income attributable to Alliant Energy common shareowners was equal to its net income attributable to Alliant Energy common shareowners for such periods. For the three and six months ended June 30, 2013 and 2012, IPL and WPL had no other comprehensive income; therefore, their comprehensive income was equal to their net income and their comprehensive income available for common stock was equal to their earnings available for common stock for such periods.