Summary Of Significant Accounting Policies

(1) 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 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 months ended March 31, 2012 and 2011, the condensed consolidated financial position at March 31, 2012 and Dec. 31, 2011, and the condensed consolidated statements of cash flows for the three months ended March 31, 2012 and 2011 have been made. Results for the three months ended March 31, 2012 are not necessarily indicative of results that may be expected for the year ending Dec. 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 have been reclassified on a basis consistent with the current period financial statement presentation. 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
	March 31,		Dec. 31,		March 31,		Dec. 31,		March 31,		Dec. 31,
	2012		2011		2012		2011		2012		2011
Tax-related	$	639.2	$	634.7	$	618.2	$	614.6	$	21.0	$	20.1
Pension and other postretirement benefits costs		510.5		514.1		263.6		264.9		246.9		249.2
Derivatives		83.1		77.7		38.1		33.5		45.0		44.2
Asset retirement obligations		57.4		65.9		39.7		48.7		17.7		17.2
Environmental-related costs		37.6		38.9		32.6		32.2		5.0		6.7
Emission allowances		30.0		30.0		30.0		30.0		—		—
IPL's electric transmission service costs		22.9		24.9		22.9		24.9		—		—
Debt redemption costs		21.3		21.8		14.7		15.1		6.6		6.7
Other		87.4		87.0		53.1		53.4		34.3		33.6

	$	1,489.4	$	1,495.0	$	1,112.9	$	1,117.3	$	376.5	$	377.7

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


	Alliant Energy				IPL				WPL
	March 31,		Dec. 31,		March 31,		Dec. 31,		March 31,		Dec. 31,
	2012		2011		2012		2011		2012		2011
Cost of removal obligations	$	407.3	$	404.9	$	264.7	$	261.9	$	142.6	$	143.0
IPL's tax benefit rider		329.4		349.6		329.4		349.6		—		—
IPL's electric transmission assets sale		42.8		45.1		42.8		45.1		—		—
Energy conservation cost recovery		37.2		29.6		7.0		4.7		30.2		24.9
Commodity cost recovery		10.5		23.8		8.6		23.2		1.9		0.6
Other		55.3		57.1		34.6		36.8		20.7		20.3

	$	882.5	$	910.1	$	687.1	$	721.3	$	195.4	$	188.8

IPL's tax benefit rider—Alliant Energy's and IPL's "IPL's tax benefit rider" regulatory liabilities in the above table decreased due to $20 million of regulatory liabilities used to credit IPL's Iowa retail electric customers' bills in the first quarter of 2012. Refer to Note 4 for additional details regarding IPL's tax benefit rider.

(c) Utility Property, Plant and Equipment -

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 March 31, 2012, WPL recorded capitalized expenditures of $84 million and allowance for funds used during construction of $5 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.

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 in the first quarter of 2011.

(d) Comprehensive Income (Loss)—For the three months ended March 31, 2012 and 2011, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income for such periods. For the three months ended March 31, 2012 and 2011, IPL and WPL had no other comprehensive income; therefore their comprehensive income (loss) was equal to their earnings available (loss) for common stock for such periods.

(e) 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.

Summary Of Significant Accounting Policies

(1) 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 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 months ended March 31, 2012 and 2011, the condensed consolidated financial position at March 31, 2012 and Dec. 31, 2011, and the condensed consolidated statements of cash flows for the three months ended March 31, 2012 and 2011 have been made. Results for the three months ended March 31, 2012 are not necessarily indicative of results that may be expected for the year ending Dec. 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 have been reclassified on a basis consistent with the current period financial statement presentation. 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
	March 31,		Dec. 31,		March 31,		Dec. 31,		March 31,		Dec. 31,
	2012		2011		2012		2011		2012		2011
Tax-related	$	639.2	$	634.7	$	618.2	$	614.6	$	21.0	$	20.1
Pension and other postretirement benefits costs		510.5		514.1		263.6		264.9		246.9		249.2
Derivatives		83.1		77.7		38.1		33.5		45.0		44.2
Asset retirement obligations		57.4		65.9		39.7		48.7		17.7		17.2
Environmental-related costs		37.6		38.9		32.6		32.2		5.0		6.7
Emission allowances		30.0		30.0		30.0		30.0		—		—
IPL's electric transmission service costs		22.9		24.9		22.9		24.9		—		—
Debt redemption costs		21.3		21.8		14.7		15.1		6.6		6.7
Other		87.4		87.0		53.1		53.4		34.3		33.6

	$	1,489.4	$	1,495.0	$	1,112.9	$	1,117.3	$	376.5	$	377.7

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


	Alliant Energy				IPL				WPL
	March 31,		Dec. 31,		March 31,		Dec. 31,		March 31,		Dec. 31,
	2012		2011		2012		2011		2012		2011
Cost of removal obligations	$	407.3	$	404.9	$	264.7	$	261.9	$	142.6	$	143.0
IPL's tax benefit rider		329.4		349.6		329.4		349.6		—		—
IPL's electric transmission assets sale		42.8		45.1		42.8		45.1		—		—
Energy conservation cost recovery		37.2		29.6		7.0		4.7		30.2		24.9
Commodity cost recovery		10.5		23.8		8.6		23.2		1.9		0.6
Other		55.3		57.1		34.6		36.8		20.7		20.3

	$	882.5	$	910.1	$	687.1	$	721.3	$	195.4	$	188.8

IPL's tax benefit rider—Alliant Energy's and IPL's "IPL's tax benefit rider" regulatory liabilities in the above table decreased due to $20 million of regulatory liabilities used to credit IPL's Iowa retail electric customers' bills in the first quarter of 2012. Refer to Note 4 for additional details regarding IPL's tax benefit rider.

(c) Utility Property, Plant and Equipment -

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 March 31, 2012, WPL recorded capitalized expenditures of $84 million and allowance for funds used during construction of $5 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.

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 in the first quarter of 2011.

(d) Comprehensive Income (Loss)—For the three months ended March 31, 2012 and 2011, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income for such periods. For the three months ended March 31, 2012 and 2011, IPL and WPL had no other comprehensive income; therefore their comprehensive income (loss) was equal to their earnings available (loss) for common stock for such periods.

(e) 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.

Summary Of Significant Accounting Policies

(1) 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 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 months ended March 31, 2012 and 2011, the condensed consolidated financial position at March 31, 2012 and Dec. 31, 2011, and the condensed consolidated statements of cash flows for the three months ended March 31, 2012 and 2011 have been made. Results for the three months ended March 31, 2012 are not necessarily indicative of results that may be expected for the year ending Dec. 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 have been reclassified on a basis consistent with the current period financial statement presentation. 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
	March 31,		Dec. 31,		March 31,		Dec. 31,		March 31,		Dec. 31,
	2012		2011		2012		2011		2012		2011
Tax-related	$	639.2	$	634.7	$	618.2	$	614.6	$	21.0	$	20.1
Pension and other postretirement benefits costs		510.5		514.1		263.6		264.9		246.9		249.2
Derivatives		83.1		77.7		38.1		33.5		45.0		44.2
Asset retirement obligations		57.4		65.9		39.7		48.7		17.7		17.2
Environmental-related costs		37.6		38.9		32.6		32.2		5.0		6.7
Emission allowances		30.0		30.0		30.0		30.0		—		—
IPL's electric transmission service costs		22.9		24.9		22.9		24.9		—		—
Debt redemption costs		21.3		21.8		14.7		15.1		6.6		6.7
Other		87.4		87.0		53.1		53.4		34.3		33.6

	$	1,489.4	$	1,495.0	$	1,112.9	$	1,117.3	$	376.5	$	377.7

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


	Alliant Energy				IPL				WPL
	March 31,		Dec. 31,		March 31,		Dec. 31,		March 31,		Dec. 31,
	2012		2011		2012		2011		2012		2011
Cost of removal obligations	$	407.3	$	404.9	$	264.7	$	261.9	$	142.6	$	143.0
IPL's tax benefit rider		329.4		349.6		329.4		349.6		—		—
IPL's electric transmission assets sale		42.8		45.1		42.8		45.1		—		—
Energy conservation cost recovery		37.2		29.6		7.0		4.7		30.2		24.9
Commodity cost recovery		10.5		23.8		8.6		23.2		1.9		0.6
Other		55.3		57.1		34.6		36.8		20.7		20.3

	$	882.5	$	910.1	$	687.1	$	721.3	$	195.4	$	188.8

IPL's tax benefit rider—Alliant Energy's and IPL's "IPL's tax benefit rider" regulatory liabilities in the above table decreased due to $20 million of regulatory liabilities used to credit IPL's Iowa retail electric customers' bills in the first quarter of 2012. Refer to Note 4 for additional details regarding IPL's tax benefit rider.

(c) Utility Property, Plant and Equipment -

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 March 31, 2012, WPL recorded capitalized expenditures of $84 million and allowance for funds used during construction of $5 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.

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 in the first quarter of 2011.

(d) Comprehensive Income (Loss)—For the three months ended March 31, 2012 and 2011, Alliant Energy had no other comprehensive income; therefore, its comprehensive income was equal to its net income for such periods. For the three months ended March 31, 2012 and 2011, IPL and WPL had no other comprehensive income; therefore their comprehensive income (loss) was equal to their earnings available (loss) for common stock for such periods.

(e) 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.