Income Taxes

12 Months Ended

Dec. 31, 2012

Income Tax [Line Items]

Income Taxes

INCOME TAXES

Income Tax Expense (Benefit) - The components of “Income tax expense (benefit)” in the Consolidated Statements of Income were as follows (in millions):

	Alliant Energy									IPL									WPL
	2012			2011			2010			2012			2011			2010			2012			2011			2010
Current tax expense (benefit):
Federal		($29.3	)		$58.6			$7.1			($7.7	)		$54.5			($22.4	)		$7.2			($4.3	)		$26.8
State	11.6			15.7			10.6			9.1			20.0			(7.6		)	(0.9		)	(7.1		)	14.7
IPL’s electric tax benefit rider	(48.3		)	(35.9		)	—			(48.3		)	(35.9		)	—			—			—			—
Deferred tax expense (benefit):
Federal	157.8			99.0			165.5			37.4			(11.6		)	100.9			81.1			111.3			63.3
State	23.9			(16.8		)	4.9			3.2			(16.4		)	(2.8		)	20.3			19.0			6.6
Production tax credits	(24.8		)	(27.1		)	(11.2		)	(12.5		)	(12.3		)	(7.7		)	(12.3		)	(14.8		)	(3.5		)
Investment tax credits	(1.7		)	(1.8		)	(1.8		)	(0.6		)	(0.6		)	(0.6		)	(1.1		)	(1.2		)	(1.2		)
Provision recorded as a change in uncertain tax positions:
Current	8.0			16.3			(84.0		)	8.1			16.6			(41.1		)	(0.1		)	(0.3		)	(41.7		)
Deferred	(7.6		)	(38.3		)	59.6			(8.2		)	(17.6		)	26.2			0.6			(20.7		)	33.3
Provision recorded as a change in accrued interest	(0.2		)	(0.5		)	(3.0		)	(0.3		)	(0.3		)	(2.6		)	(0.2		)	—			—
		$89.4			$69.2			$147.7			($19.8	)		($3.6	)		$42.3			$94.6			$81.9			$98.3

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy						IPL						WPL
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
State income taxes, net of federal benefits	5.7		4.6		4.8		5.8		4.3		4.1		5.5		5.0		5.1
State apportionment change due to announced sale of RMT	3.5		—		—		6.2		—		—		2.7		—		—
IPL’s electric tax benefit rider	(11.2	)	(8.8	)	—		(37.0	)	(26.5	)	—		—		—		—
Production tax credits	(5.8	)	(6.6	)	(2.4	)	(9.6	)	(9.1	)	(4.1	)	(4.7	)	(6.0	)	(1.4	)
Effect of rate-making on property-related differences	(5.0	)	(2.0	)	(4.2	)	(14.2	)	(5.3	)	(8.9	)	(1.1	)	(0.5	)	(1.1	)
Adjustment of prior period taxes	—		0.2		0.3		0.2		1.7		(1.8	)	(0.3	)	—		2.0
Wisconsin tax legislation	—		(4.6	)	—		—		—		—		—		—		—
Federal Health Care Legislation	—		—		1.6		—		—		2.0		—		—		1.2
Other items, net	(1.4	)	(0.9	)	(2.8	)	(1.6	)	(2.8	)	(3.5	)	(0.8	)	(0.1	)	(1.6	)
Overall income tax rate	20.8	%	16.9	%	32.3	%	(15.2	%)	(2.7	%)	22.8	%	36.3	%	33.4	%	39.2	%

State apportionment change due to announced sale of RMT - Alliant Energy, IPL and WPL utilize state apportionment projections to record their deferred tax assets and liabilities each reporting period. Deferred tax assets and liabilities for temporary differences between the tax basis of assets and liabilities and the amounts reported in the consolidated financial statements are recorded utilizing currently enacted tax rates and estimates of future state apportionment rates expected to be in effect at the time the temporary differences reverse. These state apportionment projections are most significantly impacted by the estimated amount of revenues expected in the future from each state jurisdiction for Alliant Energy’s consolidated tax group, including both its regulated operations and its non-regulated operations. In the first quarter of 2012, Alliant Energy, IPL and WPL recorded $15 million, $8 million and $7 million, respectively, of deferred income tax expense due to changes in state apportionment projections caused by the planned sale of Alliant Energy’s RMT business.

IPL’s electric tax benefit rider - In January 2011, the IUB approved an electric tax benefit rider proposed by IPL, which utilizes tax-related regulatory liabilities to credit bills of Iowa retail electric customers beginning in February 2011 to help offset the impact of recent 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 the floods in 2008. Alliant Energy’s and IPL’s effective income tax rates in 2012 and 2011 include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing the electric tax benefit rider. Refer to Note 1(b) for additional details on IPL’s electric tax benefit rider.

Production tax credits - Alliant Energy, IPL and WPL earn production tax credits from the wind projects they own and operate. Production tax credits are based on the electricity generated by each wind project during the first 10 years of operation. Alliant Energy has three wind projects that are currently generating production tax credits: WPL’s 68 MW Cedar Ridge wind project, which began generating electricity in late 2008; IPL’s 200 MW Whispering Willow - East wind project, which began generating electricity in late 2009; and WPL’s 200 MW Bent Tree - Phase I wind project, which began generating electricity in late 2010. Production tax credits (net of state tax impacts) resulting from these wind projects were as follows (in millions):

	Alliant Energy								IPL						WPL
	2012			2011		2010			2012		2011		2010		2012			2011		2010
Whispering Willow - East (IPL)		$12.5			$12.3		$7.7			$12.5		$12.3		$7.7		$—			$—		$—
Bent Tree - Phase I (WPL) (a)	9.3			9.3		1.2			—		—		—		9.3			9.3		1.2
Cedar Ridge (WPL)	4.0			4.5		3.3			—		—		—		4.0			4.5		3.3
	25.8			26.1		12.2			12.5		12.3		7.7		13.3			13.8		4.5
Deferral (a)	(1.0		)	1.0		(1.0		)	—		—		—		(1.0		)	1.0		(1.0		)
		$24.8			$27.1		$11.2			$12.5		$12.3		$7.7		$12.3			$14.8		$3.5

(a) In 2010 and 2012, WPL deferred the retail portion of the production tax credits generated in 2010 from its Bent Tree - Phase I wind project pursuant to orders issued by the PSCW in December 2009 and July 2012, respectively. As a result of a regulatory assessment completed in 2011, the retail portion of the production tax credit deferral recorded in 2010 was reversed.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s income tax expense and benefits are impacted by certain property-related differences at IPL for which deferred tax is not recognized in the income statement pursuant to Iowa rate-making principles. In 2012, the primary factor contributing to the increase in tax benefits recorded for the effect of rate-making on property-related differences is related to repair expenditures and the allocation of mixed service costs at IPL. The Internal Revenue Service (IRS) audit process was completed for allocation of mixed service costs with the income tax return for calendar year 2010 and repairs expenditures with the income tax return for calendar year 2011. The tax benefits and expenses from the change in accounting method for allocation of mixed service costs subsequent to 2010 and the tax benefits and expenses from the change in accounting method for repairs expenditures subsequent to 2011 are being recorded consistent with general Iowa rate-making principles, which resulted in an increase in tax benefits for Alliant Energy and IPL in 2012 of approximately $13 million. In 2011, a primary factor contributing to the decrease in tax benefits recorded for the effect of rate-making on property-related differences is related to a decrease in tax depreciation for IPL’s Whispering Willow - East wind project, which was placed into service in late 2009. The net income tax benefits related to tax depreciation for IPL’s Whispering Willow - East wind project were $3 million, $6 million and $12 million in 2012, 2011 and 2010, respectively.

Adjustment of prior period taxes - In 2010, the IRS completed the audits of Alliant Energy’s U.S. federal income tax returns for calendar years 2005 through 2008. The net impact of the completion of these audits and reversal of reserves for uncertain tax positions related to those audits resulted in Alliant Energy and IPL recognizing net income tax benefits in 2010 of $7 million and $5 million, respectively. These income tax benefits decreased Alliant Energy’s and IPL’s effective tax rate by 1.5% and 2.7%, respectively, and are included, along with other adjustments, in “Adjustment of prior period taxes” in the 2010 column of the above table. The net impact of the completion of the 2005 through 2008 audits and reversal of reserves for uncertain tax positions related to these audits did not have a material impact on WPL’s income tax rates for 2010.

Wisconsin tax legislation - In 2011, the 2011 Wisconsin Act 32 (Act 32) was enacted. The most significant provision of Act 32 for Alliant Energy authorizes combined groups to share net operating loss carryforwards that were incurred by group members prior to January 1, 2009 and utilize these shared net operating losses over 20 years beginning after December 31, 2011. Based on this provision of Act 32, Alliant Energy anticipated its Wisconsin combined group would be able to fully utilize $368 million of Wisconsin net operating losses incurred by Alliant Energy and Resources prior to January 1, 2009 to offset future taxable income and therefore reversed previously recorded deferred tax asset valuation allowances related to state net operating loss carryforwards of $19 million in 2011.

Federal health care legislation - In 2010, the Patient Protection and Affordable Care Act, and Health Care and Education Reconciliation Act of 2010 (Federal Health Care Legislation) were enacted. One of the most significant provisions of the Federal Health Care Legislation for Alliant Energy, IPL and WPL requires a reduction in their tax deductions for retiree health care costs beginning in 2013, to the extent their drug expenses are reimbursed under the Medicare Part D retiree drug subsidy program. The reduction in the future deductibility of retiree health care costs accrued as of December 31, 2009 required Alliant Energy, IPL and WPL to record deferred income tax expense of $7 million, $4 million and $3 million, respectively, in 2010.

Deferred Tax Assets and Liabilities - The deferred income tax (assets) and liabilities included on Alliant Energy’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,143.8		$2,143.8			$—			$1,926.4		$1,926.4
Investment in ATC	—			104.3		104.3			—			93.8		93.8
Deferred portion of tax gain on IPL’s electric transmission assets sale	—			50.7		50.7			—			75.5		75.5
Net operating losses carryforward - state	(46.8		)	—		(46.8		)	(39.9		)	—		(39.9		)
Federal credit carryforward	(133.8		)	—		(133.8		)	(107.4		)	—		(107.4		)
Regulatory liability - IPL’s tax benefit rider	(144.6		)	—		(144.6		)	(140.6		)	—		(140.6		)
Net operating losses carryforward - federal	(306.0		)	—		(306.0		)	(336.1		)	—		(336.1		)
Other	(113.7		)	208.2		94.5			(128.2		)	224.7		96.5
Subtotal	(744.9		)	2,507.0		1,762.1			(752.2		)	2,320.4		1,568.2
Valuation allowances	1.9			—		1.9			1.2			—		1.2
		($743.0	)		$2,507.0		$1,764.0			($751.0	)		$2,320.4		$1,569.4

	2012			2011
Other current assets		($170.2	)		($22.8	)
Deferred income taxes	1,934.2			1,592.2
Total deferred tax liabilities		$1,764.0			$1,569.4

The deferred income tax (assets) and liabilities included on IPL’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,243.9		$1,243.9			$—			$1,134.1		$1,134.1
Pension and other postretirement benefits obligations	—			64.9		64.9			—			67.6		67.6
Deferred portion of tax gain on electric transmission assets sale	—			50.7		50.7			—			75.5		75.5
Federal credit carryforward	(37.4		)	—		(37.4		)	(25.0		)	—		(25.0		)
Net operating losses carryforward - federal	(131.0		)	—		(131.0		)	(154.4		)	—		(154.4		)
Regulatory liability - tax benefit rider	(144.6		)	—		(144.6		)	(140.6		)	—		(140.6		)
Other	(70.4		)	31.9		(38.5		)	(76.5		)	42.7		(33.8		)
		($383.4	)		$1,391.4		$1,008.0			($396.5	)		$1,319.9		$923.4

	2012			2011
Other current assets		($79.3	)		($13.5	)
Deferred income taxes	1,087.3			936.9
Total deferred tax liabilities		$1,008.0			$923.4

The deferred income tax (assets) and liabilities included on WPL’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$793.3		$793.3			$—			$697.1		$697.1
Investment in ATC	—			104.3		104.3			—			93.8		93.8
Pension and other postretirement benefits obligations	—			46.4		46.4			—			49.6		49.6
Customer advances	(9.6		)	—		(9.6		)	(11.6		)	—		(11.6		)
Federal credit carryforward	(39.4		)	—		(39.4		)	(26.1		)	—		(26.1		)
Net operating losses carryforward - federal	(142.2		)	—		(142.2		)	(141.1		)	—		(141.1		)
Other	(31.6		)	37.3		5.7			(29.3		)	34.1		4.8
		($222.8	)		$981.3		$758.5			($208.1	)		$874.6		$666.5

	2012			2011
Other current assets		($85.6	)		($6.0	)
Deferred income taxes	844.1			672.5
Total deferred tax liabilities		$758.5			$666.5

Property -

Bonus depreciation deductions - In 2010, the Small Business Jobs Act of 2010 (SBJA) and the Tax Relief, Unemployment Insurance Reauthorization and Job Creation Act of 2010 (the Act) were enacted. The most significant provisions of the SBJA and the Act for Alliant Energy, IPL and WPL are related to the extension of bonus depreciation deductions for certain expenditures for property that are placed in service through December 31, 2012. Based on capital projects expected to be placed into service in 2012, Alliant Energy currently estimates its total bonus depreciation deductions to be claimed in its 2012 federal income tax return will be approximately $284 million ($67 million for IPL, $117 million for WPL and $100 million for Resources).

Deferred portion of tax gain on IPL’s electric transmission asset sale - Alliant Energy and IPL recognized a $527 million taxable gain upon the sale of IPL’s electric transmission assets in 2007. Under the provisions of the 2005 Energy Tax Act, Alliant Energy and IPL deferred its income tax obligation associated with the taxable gain over an eight-year period, with one-eighth of the income tax obligation recognized in each of the years of 2007 through 2014.

Carryforwards - At December 31, 2012, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$892		$306	2029
State net operating losses	871		47		2014
Federal tax credits	136		134		2022
				$487

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$382		$131	2029
State net operating losses	254		15		2018
Federal tax credits	38		37		2022
				$183

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$414		$142	2029
State net operating losses	152		8		2018
Federal tax credits	40		39		2022
				$189

At December 31, 2012, Alliant Energy’s state net operating losses carryforwards had expiration dates ranging from 2014 to 2032 with 99% expiring after 2020. At December 31, 2012, IPL’s state net operating losses carryforwards had expiration dates ranging from 2018 to 2032 with 99% expiring after 2021. At December 31, 2012, WPL’s state net operating losses carryforwards had expiration dates ranging from 2018 to 2032 with 99% expiring after 2023.

Uncertain Tax Positions - A reconciliation of the beginning and ending amounts of uncertain tax positions, excluding interest, is as follows (in millions):

	Alliant Energy									IPL									WPL
	2012			2011			2010			2012			2011			2010			2012			2011			2010
Balance, January 1		$23.5			$66.7			$101.7			$10.9			$33.0			$58.4			$12.6			$33.7			$42.1
Additions based on tax positions related to the current year	0.7			0.7			3.8			—			0.1			2.5			0.7			0.6			1.3
Additions for tax positions of prior years (a)	—			—			9.1			—			—			3.8			—			—			5.2
Reductions for tax positions of prior years (b)	(23.5		)	(43.9		)	(31.8		)	(10.9		)	(22.2		)	(22.7		)	(12.6		)	(21.7		)	(8.0		)
Settlements with taxing authorities	—			—			(16.1		)	—			—			(9.0		)	—			—			(6.9		)
Balance, December 31 (c)		$0.7			$23.5			$66.7			$—			$10.9			$33.0			$0.7			$12.6			$33.7

(a) The additions for tax positions of prior years were related to positions taken by Alliant Energy, IPL and WPL on their federal and state tax returns related to the capitalization and dispositions of property.

(b) In 2012, the reductions for tax positions of prior years were due to the finalization of Alliant Energy’s federal income tax return audits for calendar years 2005 through 2009. In 2011, the reductions for tax positions of prior years were related to guidance published by the IRS clarifying the treatment of repair expenditures for electric distribution property. In 2010, the reductions of tax positions of prior years were primarily related to deductions taken by Alliant Energy, IPL and WPL on their federal and state tax returns that were settled under audit for amounts less than the reductions of tax positions recorded.

(c) At December 31, 2012 and 2011, $0 and $10 million, respectively, of uncertain tax positions balances for both Alliant Energy and IPL included amounts recorded in regulatory liability accounts.

At December 31, 2012, 2011 and 2010, there were no penalties accrued related to uncertain tax positions. Additional information regarding uncertain tax positions at December 31 is as follows (in millions):

	Alliant Energy						IPL						WPL
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Tax positions favorably impacting future effective tax rates for continuing operations		$0.7		$—		$—		$—		$—		$—		$0.7		$—		$—
Interest accrued	—		0.4		0.7		—		0.4		0.7		—		—		—

Open tax years - Tax years that remain subject to the statute of limitations are as follows:

Major Jurisdiction	Alliant Energy			IPL			WPL
Consolidated federal income tax returns (a)	2005	-	2011	2005	-	2011	2005	-	2011
Consolidated Iowa income tax returns (b)	2005	-	2011	2005	-	2011	2005	-	2011
Wisconsin income tax returns	2005	-	2008	N/A			2005	-	2008
Wisconsin combined tax returns	2009	-	2011	2009	-	2011	2009	-	2011

(a) 2005 through 2010 are effectively settled. The statute of limitations for 2005 through 2008 has been extended to June 30, 2013. The statute of limitations for 2009 through 2011 expires three years from the extended due date of the federal tax return.

(b) 2005 through 2008 are open for federal audit adjustments only.

Reasonably possible changes to uncertain tax positions in 2013 - In 2013, statutes of limitations will expire for Alliant Energy’s, IPL’s and WPL’s tax returns in multiple state jurisdictions. The expiration of the statutes of limitations will not have any impact on Alliant Energy’s, IPL’s and WPL’s uncertain tax positions in 2013. It is reasonably possible that Alliant Energy, IPL and WPL could have material changes to their unrecognized tax benefits during the next 12 months as a result of the expected issuance in 2013 of revenue procedures clarifying the treatment of repair expenditures for electric generation and gas distribution property. An estimate of the expected changes during the next 12 months cannot be determined at this time.

IPL [Member]

Income Tax [Line Items]

Income Taxes

INCOME TAXES

Income Tax Expense (Benefit) - The components of “Income tax expense (benefit)” in the Consolidated Statements of Income were as follows (in millions):

	Alliant Energy									IPL									WPL
	2012			2011			2010			2012			2011			2010			2012			2011			2010
Current tax expense (benefit):
Federal		($29.3	)		$58.6			$7.1			($7.7	)		$54.5			($22.4	)		$7.2			($4.3	)		$26.8
State	11.6			15.7			10.6			9.1			20.0			(7.6		)	(0.9		)	(7.1		)	14.7
IPL’s electric tax benefit rider	(48.3		)	(35.9		)	—			(48.3		)	(35.9		)	—			—			—			—
Deferred tax expense (benefit):
Federal	157.8			99.0			165.5			37.4			(11.6		)	100.9			81.1			111.3			63.3
State	23.9			(16.8		)	4.9			3.2			(16.4		)	(2.8		)	20.3			19.0			6.6
Production tax credits	(24.8		)	(27.1		)	(11.2		)	(12.5		)	(12.3		)	(7.7		)	(12.3		)	(14.8		)	(3.5		)
Investment tax credits	(1.7		)	(1.8		)	(1.8		)	(0.6		)	(0.6		)	(0.6		)	(1.1		)	(1.2		)	(1.2		)
Provision recorded as a change in uncertain tax positions:
Current	8.0			16.3			(84.0		)	8.1			16.6			(41.1		)	(0.1		)	(0.3		)	(41.7		)
Deferred	(7.6		)	(38.3		)	59.6			(8.2		)	(17.6		)	26.2			0.6			(20.7		)	33.3
Provision recorded as a change in accrued interest	(0.2		)	(0.5		)	(3.0		)	(0.3		)	(0.3		)	(2.6		)	(0.2		)	—			—
		$89.4			$69.2			$147.7			($19.8	)		($3.6	)		$42.3			$94.6			$81.9			$98.3

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy						IPL						WPL
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
State income taxes, net of federal benefits	5.7		4.6		4.8		5.8		4.3		4.1		5.5		5.0		5.1
State apportionment change due to announced sale of RMT	3.5		—		—		6.2		—		—		2.7		—		—
IPL’s electric tax benefit rider	(11.2	)	(8.8	)	—		(37.0	)	(26.5	)	—		—		—		—
Production tax credits	(5.8	)	(6.6	)	(2.4	)	(9.6	)	(9.1	)	(4.1	)	(4.7	)	(6.0	)	(1.4	)
Effect of rate-making on property-related differences	(5.0	)	(2.0	)	(4.2	)	(14.2	)	(5.3	)	(8.9	)	(1.1	)	(0.5	)	(1.1	)
Adjustment of prior period taxes	—		0.2		0.3		0.2		1.7		(1.8	)	(0.3	)	—		2.0
Wisconsin tax legislation	—		(4.6	)	—		—		—		—		—		—		—
Federal Health Care Legislation	—		—		1.6		—		—		2.0		—		—		1.2
Other items, net	(1.4	)	(0.9	)	(2.8	)	(1.6	)	(2.8	)	(3.5	)	(0.8	)	(0.1	)	(1.6	)
Overall income tax rate	20.8	%	16.9	%	32.3	%	(15.2	%)	(2.7	%)	22.8	%	36.3	%	33.4	%	39.2	%

State apportionment change due to announced sale of RMT - Alliant Energy, IPL and WPL utilize state apportionment projections to record their deferred tax assets and liabilities each reporting period. Deferred tax assets and liabilities for temporary differences between the tax basis of assets and liabilities and the amounts reported in the consolidated financial statements are recorded utilizing currently enacted tax rates and estimates of future state apportionment rates expected to be in effect at the time the temporary differences reverse. These state apportionment projections are most significantly impacted by the estimated amount of revenues expected in the future from each state jurisdiction for Alliant Energy’s consolidated tax group, including both its regulated operations and its non-regulated operations. In the first quarter of 2012, Alliant Energy, IPL and WPL recorded $15 million, $8 million and $7 million, respectively, of deferred income tax expense due to changes in state apportionment projections caused by the planned sale of Alliant Energy’s RMT business.

IPL’s electric tax benefit rider - In January 2011, the IUB approved an electric tax benefit rider proposed by IPL, which utilizes tax-related regulatory liabilities to credit bills of Iowa retail electric customers beginning in February 2011 to help offset the impact of recent 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 the floods in 2008. Alliant Energy’s and IPL’s effective income tax rates in 2012 and 2011 include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing the electric tax benefit rider. Refer to Note 1(b) for additional details on IPL’s electric tax benefit rider.

Production tax credits - Alliant Energy, IPL and WPL earn production tax credits from the wind projects they own and operate. Production tax credits are based on the electricity generated by each wind project during the first 10 years of operation. Alliant Energy has three wind projects that are currently generating production tax credits: WPL’s 68 MW Cedar Ridge wind project, which began generating electricity in late 2008; IPL’s 200 MW Whispering Willow - East wind project, which began generating electricity in late 2009; and WPL’s 200 MW Bent Tree - Phase I wind project, which began generating electricity in late 2010. Production tax credits (net of state tax impacts) resulting from these wind projects were as follows (in millions):

	Alliant Energy								IPL						WPL
	2012			2011		2010			2012		2011		2010		2012			2011		2010
Whispering Willow - East (IPL)		$12.5			$12.3		$7.7			$12.5		$12.3		$7.7		$—			$—		$—
Bent Tree - Phase I (WPL) (a)	9.3			9.3		1.2			—		—		—		9.3			9.3		1.2
Cedar Ridge (WPL)	4.0			4.5		3.3			—		—		—		4.0			4.5		3.3
	25.8			26.1		12.2			12.5		12.3		7.7		13.3			13.8		4.5
Deferral (a)	(1.0		)	1.0		(1.0		)	—		—		—		(1.0		)	1.0		(1.0		)
		$24.8			$27.1		$11.2			$12.5		$12.3		$7.7		$12.3			$14.8		$3.5

(a) In 2010 and 2012, WPL deferred the retail portion of the production tax credits generated in 2010 from its Bent Tree - Phase I wind project pursuant to orders issued by the PSCW in December 2009 and July 2012, respectively. As a result of a regulatory assessment completed in 2011, the retail portion of the production tax credit deferral recorded in 2010 was reversed.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s income tax expense and benefits are impacted by certain property-related differences at IPL for which deferred tax is not recognized in the income statement pursuant to Iowa rate-making principles. In 2012, the primary factor contributing to the increase in tax benefits recorded for the effect of rate-making on property-related differences is related to repair expenditures and the allocation of mixed service costs at IPL. The Internal Revenue Service (IRS) audit process was completed for allocation of mixed service costs with the income tax return for calendar year 2010 and repairs expenditures with the income tax return for calendar year 2011. The tax benefits and expenses from the change in accounting method for allocation of mixed service costs subsequent to 2010 and the tax benefits and expenses from the change in accounting method for repairs expenditures subsequent to 2011 are being recorded consistent with general Iowa rate-making principles, which resulted in an increase in tax benefits for Alliant Energy and IPL in 2012 of approximately $13 million. In 2011, a primary factor contributing to the decrease in tax benefits recorded for the effect of rate-making on property-related differences is related to a decrease in tax depreciation for IPL’s Whispering Willow - East wind project, which was placed into service in late 2009. The net income tax benefits related to tax depreciation for IPL’s Whispering Willow - East wind project were $3 million, $6 million and $12 million in 2012, 2011 and 2010, respectively.

Adjustment of prior period taxes - In 2010, the IRS completed the audits of Alliant Energy’s U.S. federal income tax returns for calendar years 2005 through 2008. The net impact of the completion of these audits and reversal of reserves for uncertain tax positions related to those audits resulted in Alliant Energy and IPL recognizing net income tax benefits in 2010 of $7 million and $5 million, respectively. These income tax benefits decreased Alliant Energy’s and IPL’s effective tax rate by 1.5% and 2.7%, respectively, and are included, along with other adjustments, in “Adjustment of prior period taxes” in the 2010 column of the above table. The net impact of the completion of the 2005 through 2008 audits and reversal of reserves for uncertain tax positions related to these audits did not have a material impact on WPL’s income tax rates for 2010.

Wisconsin tax legislation - In 2011, the 2011 Wisconsin Act 32 (Act 32) was enacted. The most significant provision of Act 32 for Alliant Energy authorizes combined groups to share net operating loss carryforwards that were incurred by group members prior to January 1, 2009 and utilize these shared net operating losses over 20 years beginning after December 31, 2011. Based on this provision of Act 32, Alliant Energy anticipated its Wisconsin combined group would be able to fully utilize $368 million of Wisconsin net operating losses incurred by Alliant Energy and Resources prior to January 1, 2009 to offset future taxable income and therefore reversed previously recorded deferred tax asset valuation allowances related to state net operating loss carryforwards of $19 million in 2011.

Federal health care legislation - In 2010, the Patient Protection and Affordable Care Act, and Health Care and Education Reconciliation Act of 2010 (Federal Health Care Legislation) were enacted. One of the most significant provisions of the Federal Health Care Legislation for Alliant Energy, IPL and WPL requires a reduction in their tax deductions for retiree health care costs beginning in 2013, to the extent their drug expenses are reimbursed under the Medicare Part D retiree drug subsidy program. The reduction in the future deductibility of retiree health care costs accrued as of December 31, 2009 required Alliant Energy, IPL and WPL to record deferred income tax expense of $7 million, $4 million and $3 million, respectively, in 2010.

Deferred Tax Assets and Liabilities - The deferred income tax (assets) and liabilities included on Alliant Energy’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,143.8		$2,143.8			$—			$1,926.4		$1,926.4
Investment in ATC	—			104.3		104.3			—			93.8		93.8
Deferred portion of tax gain on IPL’s electric transmission assets sale	—			50.7		50.7			—			75.5		75.5
Net operating losses carryforward - state	(46.8		)	—		(46.8		)	(39.9		)	—		(39.9		)
Federal credit carryforward	(133.8		)	—		(133.8		)	(107.4		)	—		(107.4		)
Regulatory liability - IPL’s tax benefit rider	(144.6		)	—		(144.6		)	(140.6		)	—		(140.6		)
Net operating losses carryforward - federal	(306.0		)	—		(306.0		)	(336.1		)	—		(336.1		)
Other	(113.7		)	208.2		94.5			(128.2		)	224.7		96.5
Subtotal	(744.9		)	2,507.0		1,762.1			(752.2		)	2,320.4		1,568.2
Valuation allowances	1.9			—		1.9			1.2			—		1.2
		($743.0	)		$2,507.0		$1,764.0			($751.0	)		$2,320.4		$1,569.4

	2012			2011
Other current assets		($170.2	)		($22.8	)
Deferred income taxes	1,934.2			1,592.2
Total deferred tax liabilities		$1,764.0			$1,569.4

The deferred income tax (assets) and liabilities included on IPL’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,243.9		$1,243.9			$—			$1,134.1		$1,134.1
Pension and other postretirement benefits obligations	—			64.9		64.9			—			67.6		67.6
Deferred portion of tax gain on electric transmission assets sale	—			50.7		50.7			—			75.5		75.5
Federal credit carryforward	(37.4		)	—		(37.4		)	(25.0		)	—		(25.0		)
Net operating losses carryforward - federal	(131.0		)	—		(131.0		)	(154.4		)	—		(154.4		)
Regulatory liability - tax benefit rider	(144.6		)	—		(144.6		)	(140.6		)	—		(140.6		)
Other	(70.4		)	31.9		(38.5		)	(76.5		)	42.7		(33.8		)
		($383.4	)		$1,391.4		$1,008.0			($396.5	)		$1,319.9		$923.4

	2012			2011
Other current assets		($79.3	)		($13.5	)
Deferred income taxes	1,087.3			936.9
Total deferred tax liabilities		$1,008.0			$923.4

The deferred income tax (assets) and liabilities included on WPL’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$793.3		$793.3			$—			$697.1		$697.1
Investment in ATC	—			104.3		104.3			—			93.8		93.8
Pension and other postretirement benefits obligations	—			46.4		46.4			—			49.6		49.6
Customer advances	(9.6		)	—		(9.6		)	(11.6		)	—		(11.6		)
Federal credit carryforward	(39.4		)	—		(39.4		)	(26.1		)	—		(26.1		)
Net operating losses carryforward - federal	(142.2		)	—		(142.2		)	(141.1		)	—		(141.1		)
Other	(31.6		)	37.3		5.7			(29.3		)	34.1		4.8
		($222.8	)		$981.3		$758.5			($208.1	)		$874.6		$666.5

	2012			2011
Other current assets		($85.6	)		($6.0	)
Deferred income taxes	844.1			672.5
Total deferred tax liabilities		$758.5			$666.5

Property -

Bonus depreciation deductions - In 2010, the Small Business Jobs Act of 2010 (SBJA) and the Tax Relief, Unemployment Insurance Reauthorization and Job Creation Act of 2010 (the Act) were enacted. The most significant provisions of the SBJA and the Act for Alliant Energy, IPL and WPL are related to the extension of bonus depreciation deductions for certain expenditures for property that are placed in service through December 31, 2012. Based on capital projects expected to be placed into service in 2012, Alliant Energy currently estimates its total bonus depreciation deductions to be claimed in its 2012 federal income tax return will be approximately $284 million ($67 million for IPL, $117 million for WPL and $100 million for Resources).

Deferred portion of tax gain on IPL’s electric transmission asset sale - Alliant Energy and IPL recognized a $527 million taxable gain upon the sale of IPL’s electric transmission assets in 2007. Under the provisions of the 2005 Energy Tax Act, Alliant Energy and IPL deferred its income tax obligation associated with the taxable gain over an eight-year period, with one-eighth of the income tax obligation recognized in each of the years of 2007 through 2014.

Carryforwards - At December 31, 2012, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$892		$306	2029
State net operating losses	871		47		2014
Federal tax credits	136		134		2022
				$487

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$382		$131	2029
State net operating losses	254		15		2018
Federal tax credits	38		37		2022
				$183

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$414		$142	2029
State net operating losses	152		8		2018
Federal tax credits	40		39		2022
				$189

At December 31, 2012, Alliant Energy’s state net operating losses carryforwards had expiration dates ranging from 2014 to 2032 with 99% expiring after 2020. At December 31, 2012, IPL’s state net operating losses carryforwards had expiration dates ranging from 2018 to 2032 with 99% expiring after 2021. At December 31, 2012, WPL’s state net operating losses carryforwards had expiration dates ranging from 2018 to 2032 with 99% expiring after 2023.

Uncertain Tax Positions - A reconciliation of the beginning and ending amounts of uncertain tax positions, excluding interest, is as follows (in millions):

	Alliant Energy									IPL									WPL
	2012			2011			2010			2012			2011			2010			2012			2011			2010
Balance, January 1		$23.5			$66.7			$101.7			$10.9			$33.0			$58.4			$12.6			$33.7			$42.1
Additions based on tax positions related to the current year	0.7			0.7			3.8			—			0.1			2.5			0.7			0.6			1.3
Additions for tax positions of prior years (a)	—			—			9.1			—			—			3.8			—			—			5.2
Reductions for tax positions of prior years (b)	(23.5		)	(43.9		)	(31.8		)	(10.9		)	(22.2		)	(22.7		)	(12.6		)	(21.7		)	(8.0		)
Settlements with taxing authorities	—			—			(16.1		)	—			—			(9.0		)	—			—			(6.9		)
Balance, December 31 (c)		$0.7			$23.5			$66.7			$—			$10.9			$33.0			$0.7			$12.6			$33.7

(a) The additions for tax positions of prior years were related to positions taken by Alliant Energy, IPL and WPL on their federal and state tax returns related to the capitalization and dispositions of property.

(b) In 2012, the reductions for tax positions of prior years were due to the finalization of Alliant Energy’s federal income tax return audits for calendar years 2005 through 2009. In 2011, the reductions for tax positions of prior years were related to guidance published by the IRS clarifying the treatment of repair expenditures for electric distribution property. In 2010, the reductions of tax positions of prior years were primarily related to deductions taken by Alliant Energy, IPL and WPL on their federal and state tax returns that were settled under audit for amounts less than the reductions of tax positions recorded.

(c) At December 31, 2012 and 2011, $0 and $10 million, respectively, of uncertain tax positions balances for both Alliant Energy and IPL included amounts recorded in regulatory liability accounts.

At December 31, 2012, 2011 and 2010, there were no penalties accrued related to uncertain tax positions. Additional information regarding uncertain tax positions at December 31 is as follows (in millions):

	Alliant Energy						IPL						WPL
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Tax positions favorably impacting future effective tax rates for continuing operations		$0.7		$—		$—		$—		$—		$—		$0.7		$—		$—
Interest accrued	—		0.4		0.7		—		0.4		0.7		—		—		—

Open tax years - Tax years that remain subject to the statute of limitations are as follows:

Major Jurisdiction	Alliant Energy			IPL			WPL
Consolidated federal income tax returns (a)	2005	-	2011	2005	-	2011	2005	-	2011
Consolidated Iowa income tax returns (b)	2005	-	2011	2005	-	2011	2005	-	2011
Wisconsin income tax returns	2005	-	2008	N/A			2005	-	2008
Wisconsin combined tax returns	2009	-	2011	2009	-	2011	2009	-	2011

(a) 2005 through 2010 are effectively settled. The statute of limitations for 2005 through 2008 has been extended to June 30, 2013. The statute of limitations for 2009 through 2011 expires three years from the extended due date of the federal tax return.

(b) 2005 through 2008 are open for federal audit adjustments only.

Reasonably possible changes to uncertain tax positions in 2013 - In 2013, statutes of limitations will expire for Alliant Energy’s, IPL’s and WPL’s tax returns in multiple state jurisdictions. The expiration of the statutes of limitations will not have any impact on Alliant Energy’s, IPL’s and WPL’s uncertain tax positions in 2013. It is reasonably possible that Alliant Energy, IPL and WPL could have material changes to their unrecognized tax benefits during the next 12 months as a result of the expected issuance in 2013 of revenue procedures clarifying the treatment of repair expenditures for electric generation and gas distribution property. An estimate of the expected changes during the next 12 months cannot be determined at this time.

WPL [Member]

Income Tax [Line Items]

Income Taxes

INCOME TAXES

Income Tax Expense (Benefit) - The components of “Income tax expense (benefit)” in the Consolidated Statements of Income were as follows (in millions):

	Alliant Energy									IPL									WPL
	2012			2011			2010			2012			2011			2010			2012			2011			2010
Current tax expense (benefit):
Federal		($29.3	)		$58.6			$7.1			($7.7	)		$54.5			($22.4	)		$7.2			($4.3	)		$26.8
State	11.6			15.7			10.6			9.1			20.0			(7.6		)	(0.9		)	(7.1		)	14.7
IPL’s electric tax benefit rider	(48.3		)	(35.9		)	—			(48.3		)	(35.9		)	—			—			—			—
Deferred tax expense (benefit):
Federal	157.8			99.0			165.5			37.4			(11.6		)	100.9			81.1			111.3			63.3
State	23.9			(16.8		)	4.9			3.2			(16.4		)	(2.8		)	20.3			19.0			6.6
Production tax credits	(24.8		)	(27.1		)	(11.2		)	(12.5		)	(12.3		)	(7.7		)	(12.3		)	(14.8		)	(3.5		)
Investment tax credits	(1.7		)	(1.8		)	(1.8		)	(0.6		)	(0.6		)	(0.6		)	(1.1		)	(1.2		)	(1.2		)
Provision recorded as a change in uncertain tax positions:
Current	8.0			16.3			(84.0		)	8.1			16.6			(41.1		)	(0.1		)	(0.3		)	(41.7		)
Deferred	(7.6		)	(38.3		)	59.6			(8.2		)	(17.6		)	26.2			0.6			(20.7		)	33.3
Provision recorded as a change in accrued interest	(0.2		)	(0.5		)	(3.0		)	(0.3		)	(0.3		)	(2.6		)	(0.2		)	—			—
		$89.4			$69.2			$147.7			($19.8	)		($3.6	)		$42.3			$94.6			$81.9			$98.3

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy						IPL						WPL
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
State income taxes, net of federal benefits	5.7		4.6		4.8		5.8		4.3		4.1		5.5		5.0		5.1
State apportionment change due to announced sale of RMT	3.5		—		—		6.2		—		—		2.7		—		—
IPL’s electric tax benefit rider	(11.2	)	(8.8	)	—		(37.0	)	(26.5	)	—		—		—		—
Production tax credits	(5.8	)	(6.6	)	(2.4	)	(9.6	)	(9.1	)	(4.1	)	(4.7	)	(6.0	)	(1.4	)
Effect of rate-making on property-related differences	(5.0	)	(2.0	)	(4.2	)	(14.2	)	(5.3	)	(8.9	)	(1.1	)	(0.5	)	(1.1	)
Adjustment of prior period taxes	—		0.2		0.3		0.2		1.7		(1.8	)	(0.3	)	—		2.0
Wisconsin tax legislation	—		(4.6	)	—		—		—		—		—		—		—
Federal Health Care Legislation	—		—		1.6		—		—		2.0		—		—		1.2
Other items, net	(1.4	)	(0.9	)	(2.8	)	(1.6	)	(2.8	)	(3.5	)	(0.8	)	(0.1	)	(1.6	)
Overall income tax rate	20.8	%	16.9	%	32.3	%	(15.2	%)	(2.7	%)	22.8	%	36.3	%	33.4	%	39.2	%

State apportionment change due to announced sale of RMT - Alliant Energy, IPL and WPL utilize state apportionment projections to record their deferred tax assets and liabilities each reporting period. Deferred tax assets and liabilities for temporary differences between the tax basis of assets and liabilities and the amounts reported in the consolidated financial statements are recorded utilizing currently enacted tax rates and estimates of future state apportionment rates expected to be in effect at the time the temporary differences reverse. These state apportionment projections are most significantly impacted by the estimated amount of revenues expected in the future from each state jurisdiction for Alliant Energy’s consolidated tax group, including both its regulated operations and its non-regulated operations. In the first quarter of 2012, Alliant Energy, IPL and WPL recorded $15 million, $8 million and $7 million, respectively, of deferred income tax expense due to changes in state apportionment projections caused by the planned sale of Alliant Energy’s RMT business.

IPL’s electric tax benefit rider - In January 2011, the IUB approved an electric tax benefit rider proposed by IPL, which utilizes tax-related regulatory liabilities to credit bills of Iowa retail electric customers beginning in February 2011 to help offset the impact of recent 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 the floods in 2008. Alliant Energy’s and IPL’s effective income tax rates in 2012 and 2011 include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing the electric tax benefit rider. Refer to Note 1(b) for additional details on IPL’s electric tax benefit rider.

Production tax credits - Alliant Energy, IPL and WPL earn production tax credits from the wind projects they own and operate. Production tax credits are based on the electricity generated by each wind project during the first 10 years of operation. Alliant Energy has three wind projects that are currently generating production tax credits: WPL’s 68 MW Cedar Ridge wind project, which began generating electricity in late 2008; IPL’s 200 MW Whispering Willow - East wind project, which began generating electricity in late 2009; and WPL’s 200 MW Bent Tree - Phase I wind project, which began generating electricity in late 2010. Production tax credits (net of state tax impacts) resulting from these wind projects were as follows (in millions):

	Alliant Energy								IPL						WPL
	2012			2011		2010			2012		2011		2010		2012			2011		2010
Whispering Willow - East (IPL)		$12.5			$12.3		$7.7			$12.5		$12.3		$7.7		$—			$—		$—
Bent Tree - Phase I (WPL) (a)	9.3			9.3		1.2			—		—		—		9.3			9.3		1.2
Cedar Ridge (WPL)	4.0			4.5		3.3			—		—		—		4.0			4.5		3.3
	25.8			26.1		12.2			12.5		12.3		7.7		13.3			13.8		4.5
Deferral (a)	(1.0		)	1.0		(1.0		)	—		—		—		(1.0		)	1.0		(1.0		)
		$24.8			$27.1		$11.2			$12.5		$12.3		$7.7		$12.3			$14.8		$3.5

(a) In 2010 and 2012, WPL deferred the retail portion of the production tax credits generated in 2010 from its Bent Tree - Phase I wind project pursuant to orders issued by the PSCW in December 2009 and July 2012, respectively. As a result of a regulatory assessment completed in 2011, the retail portion of the production tax credit deferral recorded in 2010 was reversed.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s income tax expense and benefits are impacted by certain property-related differences at IPL for which deferred tax is not recognized in the income statement pursuant to Iowa rate-making principles. In 2012, the primary factor contributing to the increase in tax benefits recorded for the effect of rate-making on property-related differences is related to repair expenditures and the allocation of mixed service costs at IPL. The Internal Revenue Service (IRS) audit process was completed for allocation of mixed service costs with the income tax return for calendar year 2010 and repairs expenditures with the income tax return for calendar year 2011. The tax benefits and expenses from the change in accounting method for allocation of mixed service costs subsequent to 2010 and the tax benefits and expenses from the change in accounting method for repairs expenditures subsequent to 2011 are being recorded consistent with general Iowa rate-making principles, which resulted in an increase in tax benefits for Alliant Energy and IPL in 2012 of approximately $13 million. In 2011, a primary factor contributing to the decrease in tax benefits recorded for the effect of rate-making on property-related differences is related to a decrease in tax depreciation for IPL’s Whispering Willow - East wind project, which was placed into service in late 2009. The net income tax benefits related to tax depreciation for IPL’s Whispering Willow - East wind project were $3 million, $6 million and $12 million in 2012, 2011 and 2010, respectively.

Adjustment of prior period taxes - In 2010, the IRS completed the audits of Alliant Energy’s U.S. federal income tax returns for calendar years 2005 through 2008. The net impact of the completion of these audits and reversal of reserves for uncertain tax positions related to those audits resulted in Alliant Energy and IPL recognizing net income tax benefits in 2010 of $7 million and $5 million, respectively. These income tax benefits decreased Alliant Energy’s and IPL’s effective tax rate by 1.5% and 2.7%, respectively, and are included, along with other adjustments, in “Adjustment of prior period taxes” in the 2010 column of the above table. The net impact of the completion of the 2005 through 2008 audits and reversal of reserves for uncertain tax positions related to these audits did not have a material impact on WPL’s income tax rates for 2010.

Wisconsin tax legislation - In 2011, the 2011 Wisconsin Act 32 (Act 32) was enacted. The most significant provision of Act 32 for Alliant Energy authorizes combined groups to share net operating loss carryforwards that were incurred by group members prior to January 1, 2009 and utilize these shared net operating losses over 20 years beginning after December 31, 2011. Based on this provision of Act 32, Alliant Energy anticipated its Wisconsin combined group would be able to fully utilize $368 million of Wisconsin net operating losses incurred by Alliant Energy and Resources prior to January 1, 2009 to offset future taxable income and therefore reversed previously recorded deferred tax asset valuation allowances related to state net operating loss carryforwards of $19 million in 2011.

Federal health care legislation - In 2010, the Patient Protection and Affordable Care Act, and Health Care and Education Reconciliation Act of 2010 (Federal Health Care Legislation) were enacted. One of the most significant provisions of the Federal Health Care Legislation for Alliant Energy, IPL and WPL requires a reduction in their tax deductions for retiree health care costs beginning in 2013, to the extent their drug expenses are reimbursed under the Medicare Part D retiree drug subsidy program. The reduction in the future deductibility of retiree health care costs accrued as of December 31, 2009 required Alliant Energy, IPL and WPL to record deferred income tax expense of $7 million, $4 million and $3 million, respectively, in 2010.

Deferred Tax Assets and Liabilities - The deferred income tax (assets) and liabilities included on Alliant Energy’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,143.8		$2,143.8			$—			$1,926.4		$1,926.4
Investment in ATC	—			104.3		104.3			—			93.8		93.8
Deferred portion of tax gain on IPL’s electric transmission assets sale	—			50.7		50.7			—			75.5		75.5
Net operating losses carryforward - state	(46.8		)	—		(46.8		)	(39.9		)	—		(39.9		)
Federal credit carryforward	(133.8		)	—		(133.8		)	(107.4		)	—		(107.4		)
Regulatory liability - IPL’s tax benefit rider	(144.6		)	—		(144.6		)	(140.6		)	—		(140.6		)
Net operating losses carryforward - federal	(306.0		)	—		(306.0		)	(336.1		)	—		(336.1		)
Other	(113.7		)	208.2		94.5			(128.2		)	224.7		96.5
Subtotal	(744.9		)	2,507.0		1,762.1			(752.2		)	2,320.4		1,568.2
Valuation allowances	1.9			—		1.9			1.2			—		1.2
		($743.0	)		$2,507.0		$1,764.0			($751.0	)		$2,320.4		$1,569.4

	2012			2011
Other current assets		($170.2	)		($22.8	)
Deferred income taxes	1,934.2			1,592.2
Total deferred tax liabilities		$1,764.0			$1,569.4

The deferred income tax (assets) and liabilities included on IPL’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,243.9		$1,243.9			$—			$1,134.1		$1,134.1
Pension and other postretirement benefits obligations	—			64.9		64.9			—			67.6		67.6
Deferred portion of tax gain on electric transmission assets sale	—			50.7		50.7			—			75.5		75.5
Federal credit carryforward	(37.4		)	—		(37.4		)	(25.0		)	—		(25.0		)
Net operating losses carryforward - federal	(131.0		)	—		(131.0		)	(154.4		)	—		(154.4		)
Regulatory liability - tax benefit rider	(144.6		)	—		(144.6		)	(140.6		)	—		(140.6		)
Other	(70.4		)	31.9		(38.5		)	(76.5		)	42.7		(33.8		)
		($383.4	)		$1,391.4		$1,008.0			($396.5	)		$1,319.9		$923.4

	2012			2011
Other current assets		($79.3	)		($13.5	)
Deferred income taxes	1,087.3			936.9
Total deferred tax liabilities		$1,008.0			$923.4

The deferred income tax (assets) and liabilities included on WPL’s Consolidated Balance Sheets at December 31 arise from the following temporary differences (in millions):

	2012								2011
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$793.3		$793.3			$—			$697.1		$697.1
Investment in ATC	—			104.3		104.3			—			93.8		93.8
Pension and other postretirement benefits obligations	—			46.4		46.4			—			49.6		49.6
Customer advances	(9.6		)	—		(9.6		)	(11.6		)	—		(11.6		)
Federal credit carryforward	(39.4		)	—		(39.4		)	(26.1		)	—		(26.1		)
Net operating losses carryforward - federal	(142.2		)	—		(142.2		)	(141.1		)	—		(141.1		)
Other	(31.6		)	37.3		5.7			(29.3		)	34.1		4.8
		($222.8	)		$981.3		$758.5			($208.1	)		$874.6		$666.5

	2012			2011
Other current assets		($85.6	)		($6.0	)
Deferred income taxes	844.1			672.5
Total deferred tax liabilities		$758.5			$666.5

Property -

Bonus depreciation deductions - In 2010, the Small Business Jobs Act of 2010 (SBJA) and the Tax Relief, Unemployment Insurance Reauthorization and Job Creation Act of 2010 (the Act) were enacted. The most significant provisions of the SBJA and the Act for Alliant Energy, IPL and WPL are related to the extension of bonus depreciation deductions for certain expenditures for property that are placed in service through December 31, 2012. Based on capital projects expected to be placed into service in 2012, Alliant Energy currently estimates its total bonus depreciation deductions to be claimed in its 2012 federal income tax return will be approximately $284 million ($67 million for IPL, $117 million for WPL and $100 million for Resources).

Deferred portion of tax gain on IPL’s electric transmission asset sale - Alliant Energy and IPL recognized a $527 million taxable gain upon the sale of IPL’s electric transmission assets in 2007. Under the provisions of the 2005 Energy Tax Act, Alliant Energy and IPL deferred its income tax obligation associated with the taxable gain over an eight-year period, with one-eighth of the income tax obligation recognized in each of the years of 2007 through 2014.

Carryforwards - At December 31, 2012, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$892		$306	2029
State net operating losses	871		47		2014
Federal tax credits	136		134		2022
				$487

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$382		$131	2029
State net operating losses	254		15		2018
Federal tax credits	38		37		2022
				$183

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$414		$142	2029
State net operating losses	152		8		2018
Federal tax credits	40		39		2022
				$189

At December 31, 2012, Alliant Energy’s state net operating losses carryforwards had expiration dates ranging from 2014 to 2032 with 99% expiring after 2020. At December 31, 2012, IPL’s state net operating losses carryforwards had expiration dates ranging from 2018 to 2032 with 99% expiring after 2021. At December 31, 2012, WPL’s state net operating losses carryforwards had expiration dates ranging from 2018 to 2032 with 99% expiring after 2023.

Uncertain Tax Positions - A reconciliation of the beginning and ending amounts of uncertain tax positions, excluding interest, is as follows (in millions):

	Alliant Energy									IPL									WPL
	2012			2011			2010			2012			2011			2010			2012			2011			2010
Balance, January 1		$23.5			$66.7			$101.7			$10.9			$33.0			$58.4			$12.6			$33.7			$42.1
Additions based on tax positions related to the current year	0.7			0.7			3.8			—			0.1			2.5			0.7			0.6			1.3
Additions for tax positions of prior years (a)	—			—			9.1			—			—			3.8			—			—			5.2
Reductions for tax positions of prior years (b)	(23.5		)	(43.9		)	(31.8		)	(10.9		)	(22.2		)	(22.7		)	(12.6		)	(21.7		)	(8.0		)
Settlements with taxing authorities	—			—			(16.1		)	—			—			(9.0		)	—			—			(6.9		)
Balance, December 31 (c)		$0.7			$23.5			$66.7			$—			$10.9			$33.0			$0.7			$12.6			$33.7

(a) The additions for tax positions of prior years were related to positions taken by Alliant Energy, IPL and WPL on their federal and state tax returns related to the capitalization and dispositions of property.

(b) In 2012, the reductions for tax positions of prior years were due to the finalization of Alliant Energy’s federal income tax return audits for calendar years 2005 through 2009. In 2011, the reductions for tax positions of prior years were related to guidance published by the IRS clarifying the treatment of repair expenditures for electric distribution property. In 2010, the reductions of tax positions of prior years were primarily related to deductions taken by Alliant Energy, IPL and WPL on their federal and state tax returns that were settled under audit for amounts less than the reductions of tax positions recorded.

(c) At December 31, 2012 and 2011, $0 and $10 million, respectively, of uncertain tax positions balances for both Alliant Energy and IPL included amounts recorded in regulatory liability accounts.

At December 31, 2012, 2011 and 2010, there were no penalties accrued related to uncertain tax positions. Additional information regarding uncertain tax positions at December 31 is as follows (in millions):

	Alliant Energy						IPL						WPL
	2012		2011		2010		2012		2011		2010		2012		2011		2010
Tax positions favorably impacting future effective tax rates for continuing operations		$0.7		$—		$—		$—		$—		$—		$0.7		$—		$—
Interest accrued	—		0.4		0.7		—		0.4		0.7		—		—		—

Open tax years - Tax years that remain subject to the statute of limitations are as follows:

Major Jurisdiction	Alliant Energy			IPL			WPL
Consolidated federal income tax returns (a)	2005	-	2011	2005	-	2011	2005	-	2011
Consolidated Iowa income tax returns (b)	2005	-	2011	2005	-	2011	2005	-	2011
Wisconsin income tax returns	2005	-	2008	N/A			2005	-	2008
Wisconsin combined tax returns	2009	-	2011	2009	-	2011	2009	-	2011

(a) 2005 through 2010 are effectively settled. The statute of limitations for 2005 through 2008 has been extended to June 30, 2013. The statute of limitations for 2009 through 2011 expires three years from the extended due date of the federal tax return.

(b) 2005 through 2008 are open for federal audit adjustments only.

Reasonably possible changes to uncertain tax positions in 2013 - In 2013, statutes of limitations will expire for Alliant Energy’s, IPL’s and WPL’s tax returns in multiple state jurisdictions. The expiration of the statutes of limitations will not have any impact on Alliant Energy’s, IPL’s and WPL’s uncertain tax positions in 2013. It is reasonably possible that Alliant Energy, IPL and WPL could have material changes to their unrecognized tax benefits during the next 12 months as a result of the expected issuance in 2013 of revenue procedures clarifying the treatment of repair expenditures for electric generation and gas distribution property. An estimate of the expected changes during the next 12 months cannot be determined at this time.