Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax [Line Items]

Schedule of Components of 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
	2013			2012			2011			2013			2012			2011			2013			2012			2011
Current tax expense (benefit):
Federal		$4.4			($29.3	)		$58.6			$11.7			($7.7	)		$54.5			($5.7	)		$7.2			($4.3	)
State	(3.6		)	11.6			15.7			(0.1		)	9.1			20.0			6.0			(0.9		)	(7.1		)
IPL’s tax benefit riders	(52.9		)	(48.3		)	(35.9		)	(52.9		)	(48.3		)	(35.9		)	—			—			—
Deferred tax expense (benefit):
Federal	123.9			157.8			99.0			20.0			37.4			(11.6		)	92.7			81.1			111.3
State	15.6			23.9			(16.8		)	(0.8		)	3.2			(16.4		)	11.8			20.3			19.0
Production tax credits	(31.0		)	(24.8		)	(27.1		)	(14.4		)	(12.5		)	(12.3		)	(16.6		)	(12.3		)	(14.8		)
Investment tax credits	(1.6		)	(1.7		)	(1.8		)	(0.6		)	(0.6		)	(0.6		)	(1.0		)	(1.1		)	(1.2		)
Provision recorded as a change in uncertain tax positions:
Current	—			8.0			16.3			—			8.1			16.6			—			(0.1		)	(0.3		)
Deferred	(0.4		)	(7.6		)	(38.3		)	—			(8.2		)	(17.6		)	(0.4		)	0.6			(20.7		)
Provision recorded as a change in accrued interest	(0.5		)	(0.2		)	(0.5		)	(0.8		)	(0.3		)	(0.3		)	0.4			(0.2		)	—
		$53.9			$89.4			$69.2			($37.9	)		($19.8	)		($3.6	)		$87.2			$94.6			$81.9

Schedule Of Effective 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
	2013		2012		2011		2013		2012		2011		2013		2012		2011
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		5.7		4.6		5.4		5.8		4.3		6.0		5.5		5.0
IPL’s tax benefit riders	(12.1	)	(11.2	)	(8.8	)	(34.8	)	(37.0	)	(26.5	)	—		—		—
Production tax credits	(7.1	)	(5.8	)	(6.6	)	(9.5	)	(9.6	)	(9.1	)	(6.3	)	(4.7	)	(6.0	)
Effect of rate-making on property-related differences	(6.0	)	(5.0	)	(2.0	)	(15.9	)	(14.2	)	(5.3	)	(0.8	)	(1.1	)	(0.5	)
Adjustment of prior period taxes	(1.3	)	—		0.2		(3.6	)	0.2		1.7		(0.1	)	(0.3	)	—
State apportionment change due to announced sale of RMT	—		3.5		—		—		6.2		—		—		2.7		—
Wisconsin tax legislation	—		—		(4.6	)	—		—		—		—		—		—
Other items, net	(1.8	)	(1.4	)	(0.9	)	(1.5	)	(1.6	)	(2.8	)	(0.9	)	(0.8	)	(0.1	)
Overall income tax rate	12.4	%	20.8	%	16.9	%	(24.9	%)	(15.2	%)	(2.7	%)	32.9	%	36.3	%	33.4	%

Production Tax Credits (Net Of State Tax Impacts)

Production tax credits (net of state tax impacts) resulting from these wind projects are included in the table below (in millions). Production tax credits for the Whispering Willow - East and Bent Tree - Phase I wind projects increased in 2013 primarily due to higher levels of electricity output generated by the wind projects.

	Alliant Energy							IPL						WPL
	2013		2012			2011		2013		2012		2011		2013		2012			2011
Whispering Willow - East (IPL)		$14.4		$12.5			$12.3		$14.4		$12.5		$12.3		$—		$—			$—
Bent Tree - Phase I (WPL)	12.5		9.3			9.3		—		—		—		12.5		9.3			9.3
Cedar Ridge (WPL)	4.1		4.0			4.5		—		—		—		4.1		4.0			4.5
	31.0		25.8			26.1		14.4		12.5		12.3		16.6		13.3			13.8
Deferral	—		(1.0		)	1.0		—		—		—		—		(1.0		)	1.0
		$31.0		$24.8			$27.1		$14.4		$12.5		$12.3		$16.6		$12.3			$14.8

Schedule of 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):

	2013								2012
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,316.3		$2,316.3			$—			$2,143.8		$2,143.8
Investment in ATC	—			120.7		120.7			—			104.3		104.3
Net operating losses carryforward - state	(35.3		)	—		(35.3		)	(46.8		)	—		(46.8		)
Regulatory liability - IPL’s tax benefit riders	(107.8		)	—		(107.8		)	(144.6		)	—		(144.6		)
Federal credit carryforward	(167.8		)	—		(167.8		)	(133.8		)	—		(133.8		)
Net operating losses carryforward - federal	(251.9		)	—		(251.9		)	(306.0		)	—		(306.0		)
Other	(108.9		)	210.7		101.8			(113.7		)	258.9		145.2
Subtotal	(671.7		)	2,647.7		1,976.0			(744.9		)	2,507.0		1,762.1
Valuation allowances	—			—		—			1.9			—		1.9
		($671.7	)		$2,647.7		$1,976.0			($743.0	)		$2,507.0		$1,764.0

	2013			2012
Current deferred tax assets		($136.7	)		($170.2	)
Non-current deferred tax liabilities	2,112.7			1,934.2
Total net deferred tax liabilities		$1,976.0			$1,764.0

Summary Of Tax Credit Carryforwards

At December 31, 2013, 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		$735		$252	2029
State net operating losses	686		35		2018
Federal tax credits	170		168		2022
				$455

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$325		$111	2029
State net operating losses	189		10		2018
Federal tax credits	54		53		2022
				$174

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$312		$107	2029
State net operating losses	99		5		2018
Federal tax credits	58		57		2022
				$169

Summary of 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
	2013			2012			2011			2013		2012			2011			2013			2012			2011
Balance, January 1		$0.7			$23.5			$66.7			$—		$10.9			$33.0			$0.7			$12.6			$33.7
Additions based on tax positions related to the current year	—			0.7			0.7			—		—			0.1			—			0.7			0.6
Reductions for tax positions of prior years (a)	(0.7		)	(23.5		)	(43.9		)	—		(10.9		)	(22.2		)	(0.7		)	(12.6		)	(21.7		)
Balance, December 31		$—			$0.7			$23.5			$—		$—			$10.9			$—			$0.7			$12.6

(a) 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 repairs expenditures for electric distribution property.

Schedule Of Open Tax Years

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)	2010	-	2012	2010	-	2012	2010	-	2012
Consolidated Iowa income tax returns (b)	2010	-	2012	2010	-	2012	2010	-	2012
Wisconsin combined tax returns (c)	2009	-	2012	2009	-	2012	2009	-	2012

(a) 2010 through 2012 federal tax returns are effectively settled as a result of participation in the IRS Compliance Assurance Program, which allows Alliant Energy and the IRS to work together to resolve issues related to Alliant Energy’s current tax year before filing its federal income tax return. The statute of limitations for 2010 through 2012 federal tax returns expires three years from their respective filing dates.

(b) The statute of limitations for the 2010 through 2012 Iowa tax returns expires three years from their respective filing dates.

(c) The statute of limitations for the 2009 through 2012 Wisconsin combined tax returns expires four years from their respective filing dates.

IPL [Member]

Income Tax [Line Items]

Schedule of Components of 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
	2013			2012			2011			2013			2012			2011			2013			2012			2011
Current tax expense (benefit):
Federal		$4.4			($29.3	)		$58.6			$11.7			($7.7	)		$54.5			($5.7	)		$7.2			($4.3	)
State	(3.6		)	11.6			15.7			(0.1		)	9.1			20.0			6.0			(0.9		)	(7.1		)
IPL’s tax benefit riders	(52.9		)	(48.3		)	(35.9		)	(52.9		)	(48.3		)	(35.9		)	—			—			—
Deferred tax expense (benefit):
Federal	123.9			157.8			99.0			20.0			37.4			(11.6		)	92.7			81.1			111.3
State	15.6			23.9			(16.8		)	(0.8		)	3.2			(16.4		)	11.8			20.3			19.0
Production tax credits	(31.0		)	(24.8		)	(27.1		)	(14.4		)	(12.5		)	(12.3		)	(16.6		)	(12.3		)	(14.8		)
Investment tax credits	(1.6		)	(1.7		)	(1.8		)	(0.6		)	(0.6		)	(0.6		)	(1.0		)	(1.1		)	(1.2		)
Provision recorded as a change in uncertain tax positions:
Current	—			8.0			16.3			—			8.1			16.6			—			(0.1		)	(0.3		)
Deferred	(0.4		)	(7.6		)	(38.3		)	—			(8.2		)	(17.6		)	(0.4		)	0.6			(20.7		)
Provision recorded as a change in accrued interest	(0.5		)	(0.2		)	(0.5		)	(0.8		)	(0.3		)	(0.3		)	0.4			(0.2		)	—
		$53.9			$89.4			$69.2			($37.9	)		($19.8	)		($3.6	)		$87.2			$94.6			$81.9

Schedule Of Effective 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
	2013		2012		2011		2013		2012		2011		2013		2012		2011
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		5.7		4.6		5.4		5.8		4.3		6.0		5.5		5.0
IPL’s tax benefit riders	(12.1	)	(11.2	)	(8.8	)	(34.8	)	(37.0	)	(26.5	)	—		—		—
Production tax credits	(7.1	)	(5.8	)	(6.6	)	(9.5	)	(9.6	)	(9.1	)	(6.3	)	(4.7	)	(6.0	)
Effect of rate-making on property-related differences	(6.0	)	(5.0	)	(2.0	)	(15.9	)	(14.2	)	(5.3	)	(0.8	)	(1.1	)	(0.5	)
Adjustment of prior period taxes	(1.3	)	—		0.2		(3.6	)	0.2		1.7		(0.1	)	(0.3	)	—
State apportionment change due to announced sale of RMT	—		3.5		—		—		6.2		—		—		2.7		—
Wisconsin tax legislation	—		—		(4.6	)	—		—		—		—		—		—
Other items, net	(1.8	)	(1.4	)	(0.9	)	(1.5	)	(1.6	)	(2.8	)	(0.9	)	(0.8	)	(0.1	)
Overall income tax rate	12.4	%	20.8	%	16.9	%	(24.9	%)	(15.2	%)	(2.7	%)	32.9	%	36.3	%	33.4	%

Production Tax Credits (Net Of State Tax Impacts)

Production tax credits (net of state tax impacts) resulting from these wind projects are included in the table below (in millions). Production tax credits for the Whispering Willow - East and Bent Tree - Phase I wind projects increased in 2013 primarily due to higher levels of electricity output generated by the wind projects.

	Alliant Energy							IPL						WPL
	2013		2012			2011		2013		2012		2011		2013		2012			2011
Whispering Willow - East (IPL)		$14.4		$12.5			$12.3		$14.4		$12.5		$12.3		$—		$—			$—
Bent Tree - Phase I (WPL)	12.5		9.3			9.3		—		—		—		12.5		9.3			9.3
Cedar Ridge (WPL)	4.1		4.0			4.5		—		—		—		4.1		4.0			4.5
	31.0		25.8			26.1		14.4		12.5		12.3		16.6		13.3			13.8
Deferral	—		(1.0		)	1.0		—		—		—		—		(1.0		)	1.0
		$31.0		$24.8			$27.1		$14.4		$12.5		$12.3		$16.6		$12.3			$14.8

Schedule of Deferred Tax Assets and Liabilities

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):

	2013								2012
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,338.1		$1,338.1			$—			$1,243.9		$1,243.9
Federal credit carryforward	(52.9		)	—		(52.9		)	(37.4		)	—		(37.4		)
Regulatory liability - tax benefit riders	(107.8		)	—		(107.8		)	(144.6		)	—		(144.6		)
Net operating losses carryforward - federal	(111.3		)	—		(111.3		)	(131.0		)	—		(131.0		)
Other	(64.0		)	103.2		39.2			(70.4		)	147.5		77.1
		($336.0	)		$1,441.3		$1,105.3			($383.4	)		$1,391.4		$1,008.0

	2013			2012
Current deferred tax assets		($87.7	)		($79.3	)
Non-current deferred tax liabilities	1,193.0			1,087.3
Total net deferred tax liabilities		$1,105.3			$1,008.0

Summary Of Tax Credit Carryforwards

At December 31, 2013, 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		$735		$252	2029
State net operating losses	686		35		2018
Federal tax credits	170		168		2022
				$455

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$325		$111	2029
State net operating losses	189		10		2018
Federal tax credits	54		53		2022
				$174

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$312		$107	2029
State net operating losses	99		5		2018
Federal tax credits	58		57		2022
				$169

Summary of 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
	2013			2012			2011			2013		2012			2011			2013			2012			2011
Balance, January 1		$0.7			$23.5			$66.7			$—		$10.9			$33.0			$0.7			$12.6			$33.7
Additions based on tax positions related to the current year	—			0.7			0.7			—		—			0.1			—			0.7			0.6
Reductions for tax positions of prior years (a)	(0.7		)	(23.5		)	(43.9		)	—		(10.9		)	(22.2		)	(0.7		)	(12.6		)	(21.7		)
Balance, December 31		$—			$0.7			$23.5			$—		$—			$10.9			$—			$0.7			$12.6

(a) 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 repairs expenditures for electric distribution property.

Schedule Of Open Tax Years

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)	2010	-	2012	2010	-	2012	2010	-	2012
Consolidated Iowa income tax returns (b)	2010	-	2012	2010	-	2012	2010	-	2012
Wisconsin combined tax returns (c)	2009	-	2012	2009	-	2012	2009	-	2012

(a) 2010 through 2012 federal tax returns are effectively settled as a result of participation in the IRS Compliance Assurance Program, which allows Alliant Energy and the IRS to work together to resolve issues related to Alliant Energy’s current tax year before filing its federal income tax return. The statute of limitations for 2010 through 2012 federal tax returns expires three years from their respective filing dates.

(b) The statute of limitations for the 2010 through 2012 Iowa tax returns expires three years from their respective filing dates.

(c) The statute of limitations for the 2009 through 2012 Wisconsin combined tax returns expires four years from their respective filing dates.

WPL [Member]

Income Tax [Line Items]

Schedule of Components of 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
	2013			2012			2011			2013			2012			2011			2013			2012			2011
Current tax expense (benefit):
Federal		$4.4			($29.3	)		$58.6			$11.7			($7.7	)		$54.5			($5.7	)		$7.2			($4.3	)
State	(3.6		)	11.6			15.7			(0.1		)	9.1			20.0			6.0			(0.9		)	(7.1		)
IPL’s tax benefit riders	(52.9		)	(48.3		)	(35.9		)	(52.9		)	(48.3		)	(35.9		)	—			—			—
Deferred tax expense (benefit):
Federal	123.9			157.8			99.0			20.0			37.4			(11.6		)	92.7			81.1			111.3
State	15.6			23.9			(16.8		)	(0.8		)	3.2			(16.4		)	11.8			20.3			19.0
Production tax credits	(31.0		)	(24.8		)	(27.1		)	(14.4		)	(12.5		)	(12.3		)	(16.6		)	(12.3		)	(14.8		)
Investment tax credits	(1.6		)	(1.7		)	(1.8		)	(0.6		)	(0.6		)	(0.6		)	(1.0		)	(1.1		)	(1.2		)
Provision recorded as a change in uncertain tax positions:
Current	—			8.0			16.3			—			8.1			16.6			—			(0.1		)	(0.3		)
Deferred	(0.4		)	(7.6		)	(38.3		)	—			(8.2		)	(17.6		)	(0.4		)	0.6			(20.7		)
Provision recorded as a change in accrued interest	(0.5		)	(0.2		)	(0.5		)	(0.8		)	(0.3		)	(0.3		)	0.4			(0.2		)	—
		$53.9			$89.4			$69.2			($37.9	)		($19.8	)		($3.6	)		$87.2			$94.6			$81.9

Schedule Of Effective 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
	2013		2012		2011		2013		2012		2011		2013		2012		2011
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		5.7		4.6		5.4		5.8		4.3		6.0		5.5		5.0
IPL’s tax benefit riders	(12.1	)	(11.2	)	(8.8	)	(34.8	)	(37.0	)	(26.5	)	—		—		—
Production tax credits	(7.1	)	(5.8	)	(6.6	)	(9.5	)	(9.6	)	(9.1	)	(6.3	)	(4.7	)	(6.0	)
Effect of rate-making on property-related differences	(6.0	)	(5.0	)	(2.0	)	(15.9	)	(14.2	)	(5.3	)	(0.8	)	(1.1	)	(0.5	)
Adjustment of prior period taxes	(1.3	)	—		0.2		(3.6	)	0.2		1.7		(0.1	)	(0.3	)	—
State apportionment change due to announced sale of RMT	—		3.5		—		—		6.2		—		—		2.7		—
Wisconsin tax legislation	—		—		(4.6	)	—		—		—		—		—		—
Other items, net	(1.8	)	(1.4	)	(0.9	)	(1.5	)	(1.6	)	(2.8	)	(0.9	)	(0.8	)	(0.1	)
Overall income tax rate	12.4	%	20.8	%	16.9	%	(24.9	%)	(15.2	%)	(2.7	%)	32.9	%	36.3	%	33.4	%

Production Tax Credits (Net Of State Tax Impacts)

Production tax credits (net of state tax impacts) resulting from these wind projects are included in the table below (in millions). Production tax credits for the Whispering Willow - East and Bent Tree - Phase I wind projects increased in 2013 primarily due to higher levels of electricity output generated by the wind projects.

	Alliant Energy							IPL						WPL
	2013		2012			2011		2013		2012		2011		2013		2012			2011
Whispering Willow - East (IPL)		$14.4		$12.5			$12.3		$14.4		$12.5		$12.3		$—		$—			$—
Bent Tree - Phase I (WPL)	12.5		9.3			9.3		—		—		—		12.5		9.3			9.3
Cedar Ridge (WPL)	4.1		4.0			4.5		—		—		—		4.1		4.0			4.5
	31.0		25.8			26.1		14.4		12.5		12.3		16.6		13.3			13.8
Deferral	—		(1.0		)	1.0		—		—		—		—		(1.0		)	1.0
		$31.0		$24.8			$27.1		$14.4		$12.5		$12.3		$16.6		$12.3			$14.8

Schedule of Deferred Tax Assets and Liabilities

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):

	2013								2012
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$859.1		$859.1			$—			$793.3		$793.3
Investment in ATC	—			120.7		120.7			—			104.3		104.3
Federal credit carryforward	(57.1		)	—		(57.1		)	(39.4		)	—		(39.4		)
Net operating losses carryforward - federal	(106.9		)	—		(106.9		)	(142.2		)	—		(142.2		)
Other	(37.6		)	75.6		38.0			(41.2		)	83.7		42.5
		($201.6	)		$1,055.4		$853.8			($222.8	)		$981.3		$758.5

	2013			2012
Current deferred tax assets		($43.3	)		($85.6	)
Non-current deferred tax liabilities	897.1			844.1
Total net deferred tax liabilities		$853.8			$758.5

Summary Of Tax Credit Carryforwards

At December 31, 2013, 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		$735		$252	2029
State net operating losses	686		35		2018
Federal tax credits	170		168		2022
				$455

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$325		$111	2029
State net operating losses	189		10		2018
Federal tax credits	54		53		2022
				$174

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$312		$107	2029
State net operating losses	99		5		2018
Federal tax credits	58		57		2022
				$169

Summary of 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
	2013			2012			2011			2013		2012			2011			2013			2012			2011
Balance, January 1		$0.7			$23.5			$66.7			$—		$10.9			$33.0			$0.7			$12.6			$33.7
Additions based on tax positions related to the current year	—			0.7			0.7			—		—			0.1			—			0.7			0.6
Reductions for tax positions of prior years (a)	(0.7		)	(23.5		)	(43.9		)	—		(10.9		)	(22.2		)	(0.7		)	(12.6		)	(21.7		)
Balance, December 31		$—			$0.7			$23.5			$—		$—			$10.9			$—			$0.7			$12.6

(a) 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 repairs expenditures for electric distribution property.

Schedule Of Open Tax Years

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)	2010	-	2012	2010	-	2012	2010	-	2012
Consolidated Iowa income tax returns (b)	2010	-	2012	2010	-	2012	2010	-	2012
Wisconsin combined tax returns (c)	2009	-	2012	2009	-	2012	2009	-	2012

(a) 2010 through 2012 federal tax returns are effectively settled as a result of participation in the IRS Compliance Assurance Program, which allows Alliant Energy and the IRS to work together to resolve issues related to Alliant Energy’s current tax year before filing its federal income tax return. The statute of limitations for 2010 through 2012 federal tax returns expires three years from their respective filing dates.

(b) The statute of limitations for the 2010 through 2012 Iowa tax returns expires three years from their respective filing dates.

(c) The statute of limitations for the 2009 through 2012 Wisconsin combined tax returns expires four years from their respective filing dates.