Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax [Line Items]

Schedule of Components of Income Tax Expense (Benefit)

The components of “Income tax expense (benefit)” in the income statements were as follows (in millions):

	Alliant Energy									IPL									WPL
	2015			2014			2013			2015			2014			2013			2015			2014			2013
Current tax expense (benefit):
Federal		$2.0			$36.6			$4.4			($14.1	)		$8.9			$10.2			$4.7			$2.0			($0.3	)
State	3.2			9.3			(3.6		)	11.5			10.4			4.2			0.6			0.8			(4.3		)
IPL’s tax benefit riders	(49.0		)	(56.7		)	(52.9		)	(49.0		)	(56.7		)	(52.9		)	—			—			—
Deferred tax expense (benefit):
Federal	120.8			83.5			123.9			40.7			10.8			21.7			76.8			81.1			84.0
State	27.9			4.6			15.6			3.3			(7.9		)	(4.0		)	20.2			20.0			24.1
Production tax credits	(33.1		)	(31.3		)	(31.0		)	(14.5		)	(13.8		)	(14.1		)	(18.6		)	(17.5		)	(16.9		)
Investment tax credits	(1.4		)	(1.6		)	(1.6		)	(0.6		)	(0.6		)	(0.6		)	(0.8		)	(1.0		)	(1.0		)
Provision recorded as a change in uncertain tax positions:
Deferred	—			—			(0.4		)	—			—			—			—			—			(0.4		)
Provision recorded as a change in accrued interest	—			(0.1		)	(0.5		)	—			—			(0.8		)	—			(0.1		)	0.4
		$70.4			$44.3			$53.9			($22.7	)		($48.9	)		($36.3	)		$82.9			$85.3			$85.6

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
	2015		2014		2013		2015		2014		2013		2015		2014		2013
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	5.2		5.4		5.7		6.2		6.1		6.3		5.1		5.1		5.5
IPL’s tax benefit riders	(10.6	)	(12.9	)	(12.1	)	(28.3	)	(39.6	)	(34.8	)	—		—		—
Effect of rate-making on property-related differences	(6.8	)	(7.5	)	(6.0	)	(17.2	)	(21.9	)	(15.9	)	(0.5	)	(0.7	)	(0.8	)
Production tax credits	(7.2	)	(7.1	)	(7.1	)	(8.3	)	(9.6	)	(9.3	)	(7.1	)	(6.6	)	(6.4	)
Adjustment of prior period taxes	0.8		(1.3	)	(1.3	)	0.7		(3.0	)	(3.6	)	0.1		—		(0.2	)
Other items, net	(1.1	)	(1.5	)	(1.8	)	(1.2	)	(1.2	)	(1.6	)	(0.8	)	(0.8	)	(0.8	)
Overall income tax rate	15.3	%	10.1	%	12.4	%	(13.1	%)	(34.2	%)	(23.9	%)	31.8	%	32.0	%	32.3	%

Production Tax Credits (Net Of State Tax Impacts)

Details regarding production tax credits (net of state tax impacts) related to various wind farms are as follows (dollars in millions):

	End of Production	Nameplate
	Tax Credit Generation	Capacity in MW	2015		2014		2013
Cedar Ridge (WPL)	December 2018	68		$4.5		$4.1		$4.2
Bent Tree (WPL)	February 2021	201	14.1		13.4		12.7
Subtotal (WPL)			18.6		17.5		16.9
Whispering Willow - East (IPL)	December 2019	200	14.5		13.8		14.1
				$33.1		$31.3		$31.0

Schedule of Deferred Tax Assets and Liabilities

The deferred tax (assets) and liabilities included on the balance sheets at December 31 arise from the following temporary differences (in millions):

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,762.9		$2,762.9			$—			$2,627.8		$2,627.8
Investment in ATC	—			138.1		138.1			—			131.6		131.6
Net operating losses carryforwards - state	(38.3		)	—		(38.3		)	(45.7		)	—		(45.7		)
Regulatory liability - IPL’s tax benefit riders	(66.1		)	—		(66.1		)	(100.9		)	—		(100.9		)
Federal credit carryforwards	(236.4		)	—		(236.4		)	(201.0		)	—		(201.0		)
Net operating losses carryforwards - federal	(250.9		)	—		(250.9		)	(332.8		)	—		(332.8		)
Other	(85.4		)	157.3		71.9			(88.1		)	180.1		92.0
		($677.1	)		$3,058.3		$2,381.2			($768.5	)		$2,939.5		$2,171.0

	2015		2014
Current deferred tax assets	N/A			($150.1	)
Non-current deferred tax liabilities		$2,381.2	2,321.1
Total net deferred tax liabilities		$2,381.2		$2,171.0

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,587.8		$1,587.8			$—			$1,545.1		$1,545.1
Regulatory liability - tax benefit riders	(66.1		)	—		(66.1		)	(100.9		)	—		(100.9		)
Federal credit carryforwards	(81.7		)	—		(81.7		)	(66.5		)	—		(66.5		)
Net operating losses carryforwards - federal	(113.1		)	—		(113.1		)	(157.8		)	—		(157.8		)
Other	(36.7		)	87.8		51.1			(37.1		)	83.5		46.4
		($297.6	)		$1,675.6		$1,378.0			($362.3	)		$1,628.6		$1,266.3

	2015		2014
Current deferred tax assets	N/A			($104.0	)
Non-current deferred tax liabilities		$1,378.0	1,370.3
Total net deferred tax liabilities		$1,378.0		$1,266.3

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,027.0		$1,027.0			$—			$963.0		$963.0
Investment in ATC	—			138.9		138.9			—			132.1		132.1
Federal credit carryforwards	(95.5		)	—		(95.5		)	(76.7		)	—		(76.7		)
Net operating losses carryforwards - federal	(105.1		)	—		(105.1		)	(131.6		)	—		(131.6		)
Other	(27.8		)	67.9		40.1			(37.1		)	79.7		42.6
		($228.4	)		$1,233.8		$1,005.4			($245.4	)		$1,174.8		$929.4

	2015		2014
Current deferred tax assets	N/A			($37.7	)
Non-current deferred tax liabilities		$1,005.4	967.1
Total net deferred tax liabilities		$1,005.4		$929.4

Summary Of Tax Credit Carryforwards

At December 31, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

		Alliant Energy				IPL				WPL
	Earliest	Tax		Deferred		Tax		Deferred		Tax		Deferred
	Expiration Date	Carryforwards		Tax Assets		Carryforwards		Tax Assets		Carryforwards		Tax Assets
Federal net operating losses	2030		$732		$251		$336		$113		$300		$105
State net operating losses	2018	766		38		20		1		76		4
Federal tax credits	2022	240		236		85		82		96		96
					$525				$196				$205

Schedule Of Open Tax Years

Open tax years - Tax years that remain subject to the statute of limitations in the major jurisdictions for each of Alliant Energy, IPL and WPL are as follows:

Consolidated federal income tax returns (a)	2012	-	2014
Consolidated Iowa income tax returns (b)	2012	-	2014
Wisconsin combined tax returns (c)	2011	-	2014

(a) These 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 these federal tax returns expires three years from each filing date.

(b) The statute of limitations for these Iowa tax returns expires three years from each filing date.

(c) The statute of limitations for these Wisconsin combined tax returns expires four years from each filing date.

IPL [Member]

Income Tax [Line Items]

Schedule of Components of Income Tax Expense (Benefit)

The components of “Income tax expense (benefit)” in the income statements were as follows (in millions):

	Alliant Energy									IPL									WPL
	2015			2014			2013			2015			2014			2013			2015			2014			2013
Current tax expense (benefit):
Federal		$2.0			$36.6			$4.4			($14.1	)		$8.9			$10.2			$4.7			$2.0			($0.3	)
State	3.2			9.3			(3.6		)	11.5			10.4			4.2			0.6			0.8			(4.3		)
IPL’s tax benefit riders	(49.0		)	(56.7		)	(52.9		)	(49.0		)	(56.7		)	(52.9		)	—			—			—
Deferred tax expense (benefit):
Federal	120.8			83.5			123.9			40.7			10.8			21.7			76.8			81.1			84.0
State	27.9			4.6			15.6			3.3			(7.9		)	(4.0		)	20.2			20.0			24.1
Production tax credits	(33.1		)	(31.3		)	(31.0		)	(14.5		)	(13.8		)	(14.1		)	(18.6		)	(17.5		)	(16.9		)
Investment tax credits	(1.4		)	(1.6		)	(1.6		)	(0.6		)	(0.6		)	(0.6		)	(0.8		)	(1.0		)	(1.0		)
Provision recorded as a change in uncertain tax positions:
Deferred	—			—			(0.4		)	—			—			—			—			—			(0.4		)
Provision recorded as a change in accrued interest	—			(0.1		)	(0.5		)	—			—			(0.8		)	—			(0.1		)	0.4
		$70.4			$44.3			$53.9			($22.7	)		($48.9	)		($36.3	)		$82.9			$85.3			$85.6

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
	2015		2014		2013		2015		2014		2013		2015		2014		2013
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	5.2		5.4		5.7		6.2		6.1		6.3		5.1		5.1		5.5
IPL’s tax benefit riders	(10.6	)	(12.9	)	(12.1	)	(28.3	)	(39.6	)	(34.8	)	—		—		—
Effect of rate-making on property-related differences	(6.8	)	(7.5	)	(6.0	)	(17.2	)	(21.9	)	(15.9	)	(0.5	)	(0.7	)	(0.8	)
Production tax credits	(7.2	)	(7.1	)	(7.1	)	(8.3	)	(9.6	)	(9.3	)	(7.1	)	(6.6	)	(6.4	)
Adjustment of prior period taxes	0.8		(1.3	)	(1.3	)	0.7		(3.0	)	(3.6	)	0.1		—		(0.2	)
Other items, net	(1.1	)	(1.5	)	(1.8	)	(1.2	)	(1.2	)	(1.6	)	(0.8	)	(0.8	)	(0.8	)
Overall income tax rate	15.3	%	10.1	%	12.4	%	(13.1	%)	(34.2	%)	(23.9	%)	31.8	%	32.0	%	32.3	%

Production Tax Credits (Net Of State Tax Impacts)

Details regarding production tax credits (net of state tax impacts) related to various wind farms are as follows (dollars in millions):

	End of Production	Nameplate
	Tax Credit Generation	Capacity in MW	2015		2014		2013
Cedar Ridge (WPL)	December 2018	68		$4.5		$4.1		$4.2
Bent Tree (WPL)	February 2021	201	14.1		13.4		12.7
Subtotal (WPL)			18.6		17.5		16.9
Whispering Willow - East (IPL)	December 2019	200	14.5		13.8		14.1
				$33.1		$31.3		$31.0

Schedule of Deferred Tax Assets and Liabilities

The deferred tax (assets) and liabilities included on the balance sheets at December 31 arise from the following temporary differences (in millions):

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,762.9		$2,762.9			$—			$2,627.8		$2,627.8
Investment in ATC	—			138.1		138.1			—			131.6		131.6
Net operating losses carryforwards - state	(38.3		)	—		(38.3		)	(45.7		)	—		(45.7		)
Regulatory liability - IPL’s tax benefit riders	(66.1		)	—		(66.1		)	(100.9		)	—		(100.9		)
Federal credit carryforwards	(236.4		)	—		(236.4		)	(201.0		)	—		(201.0		)
Net operating losses carryforwards - federal	(250.9		)	—		(250.9		)	(332.8		)	—		(332.8		)
Other	(85.4		)	157.3		71.9			(88.1		)	180.1		92.0
		($677.1	)		$3,058.3		$2,381.2			($768.5	)		$2,939.5		$2,171.0

	2015		2014
Current deferred tax assets	N/A			($150.1	)
Non-current deferred tax liabilities		$2,381.2	2,321.1
Total net deferred tax liabilities		$2,381.2		$2,171.0

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,587.8		$1,587.8			$—			$1,545.1		$1,545.1
Regulatory liability - tax benefit riders	(66.1		)	—		(66.1		)	(100.9		)	—		(100.9		)
Federal credit carryforwards	(81.7		)	—		(81.7		)	(66.5		)	—		(66.5		)
Net operating losses carryforwards - federal	(113.1		)	—		(113.1		)	(157.8		)	—		(157.8		)
Other	(36.7		)	87.8		51.1			(37.1		)	83.5		46.4
		($297.6	)		$1,675.6		$1,378.0			($362.3	)		$1,628.6		$1,266.3

	2015		2014
Current deferred tax assets	N/A			($104.0	)
Non-current deferred tax liabilities		$1,378.0	1,370.3
Total net deferred tax liabilities		$1,378.0		$1,266.3

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,027.0		$1,027.0			$—			$963.0		$963.0
Investment in ATC	—			138.9		138.9			—			132.1		132.1
Federal credit carryforwards	(95.5		)	—		(95.5		)	(76.7		)	—		(76.7		)
Net operating losses carryforwards - federal	(105.1		)	—		(105.1		)	(131.6		)	—		(131.6		)
Other	(27.8		)	67.9		40.1			(37.1		)	79.7		42.6
		($228.4	)		$1,233.8		$1,005.4			($245.4	)		$1,174.8		$929.4

	2015		2014
Current deferred tax assets	N/A			($37.7	)
Non-current deferred tax liabilities		$1,005.4	967.1
Total net deferred tax liabilities		$1,005.4		$929.4

Summary Of Tax Credit Carryforwards

At December 31, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

		Alliant Energy				IPL				WPL
	Earliest	Tax		Deferred		Tax		Deferred		Tax		Deferred
	Expiration Date	Carryforwards		Tax Assets		Carryforwards		Tax Assets		Carryforwards		Tax Assets
Federal net operating losses	2030		$732		$251		$336		$113		$300		$105
State net operating losses	2018	766		38		20		1		76		4
Federal tax credits	2022	240		236		85		82		96		96
					$525				$196				$205

Schedule Of Open Tax Years

Open tax years - Tax years that remain subject to the statute of limitations in the major jurisdictions for each of Alliant Energy, IPL and WPL are as follows:

Consolidated federal income tax returns (a)	2012	-	2014
Consolidated Iowa income tax returns (b)	2012	-	2014
Wisconsin combined tax returns (c)	2011	-	2014

(a) These 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 these federal tax returns expires three years from each filing date.

(b) The statute of limitations for these Iowa tax returns expires three years from each filing date.

(c) The statute of limitations for these Wisconsin combined tax returns expires four years from each filing date.

WPL [Member]

Income Tax [Line Items]

Schedule of Components of Income Tax Expense (Benefit)

The components of “Income tax expense (benefit)” in the income statements were as follows (in millions):

	Alliant Energy									IPL									WPL
	2015			2014			2013			2015			2014			2013			2015			2014			2013
Current tax expense (benefit):
Federal		$2.0			$36.6			$4.4			($14.1	)		$8.9			$10.2			$4.7			$2.0			($0.3	)
State	3.2			9.3			(3.6		)	11.5			10.4			4.2			0.6			0.8			(4.3		)
IPL’s tax benefit riders	(49.0		)	(56.7		)	(52.9		)	(49.0		)	(56.7		)	(52.9		)	—			—			—
Deferred tax expense (benefit):
Federal	120.8			83.5			123.9			40.7			10.8			21.7			76.8			81.1			84.0
State	27.9			4.6			15.6			3.3			(7.9		)	(4.0		)	20.2			20.0			24.1
Production tax credits	(33.1		)	(31.3		)	(31.0		)	(14.5		)	(13.8		)	(14.1		)	(18.6		)	(17.5		)	(16.9		)
Investment tax credits	(1.4		)	(1.6		)	(1.6		)	(0.6		)	(0.6		)	(0.6		)	(0.8		)	(1.0		)	(1.0		)
Provision recorded as a change in uncertain tax positions:
Deferred	—			—			(0.4		)	—			—			—			—			—			(0.4		)
Provision recorded as a change in accrued interest	—			(0.1		)	(0.5		)	—			—			(0.8		)	—			(0.1		)	0.4
		$70.4			$44.3			$53.9			($22.7	)		($48.9	)		($36.3	)		$82.9			$85.3			$85.6

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
	2015		2014		2013		2015		2014		2013		2015		2014		2013
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	5.2		5.4		5.7		6.2		6.1		6.3		5.1		5.1		5.5
IPL’s tax benefit riders	(10.6	)	(12.9	)	(12.1	)	(28.3	)	(39.6	)	(34.8	)	—		—		—
Effect of rate-making on property-related differences	(6.8	)	(7.5	)	(6.0	)	(17.2	)	(21.9	)	(15.9	)	(0.5	)	(0.7	)	(0.8	)
Production tax credits	(7.2	)	(7.1	)	(7.1	)	(8.3	)	(9.6	)	(9.3	)	(7.1	)	(6.6	)	(6.4	)
Adjustment of prior period taxes	0.8		(1.3	)	(1.3	)	0.7		(3.0	)	(3.6	)	0.1		—		(0.2	)
Other items, net	(1.1	)	(1.5	)	(1.8	)	(1.2	)	(1.2	)	(1.6	)	(0.8	)	(0.8	)	(0.8	)
Overall income tax rate	15.3	%	10.1	%	12.4	%	(13.1	%)	(34.2	%)	(23.9	%)	31.8	%	32.0	%	32.3	%

Production Tax Credits (Net Of State Tax Impacts)

Details regarding production tax credits (net of state tax impacts) related to various wind farms are as follows (dollars in millions):

	End of Production	Nameplate
	Tax Credit Generation	Capacity in MW	2015		2014		2013
Cedar Ridge (WPL)	December 2018	68		$4.5		$4.1		$4.2
Bent Tree (WPL)	February 2021	201	14.1		13.4		12.7
Subtotal (WPL)			18.6		17.5		16.9
Whispering Willow - East (IPL)	December 2019	200	14.5		13.8		14.1
				$33.1		$31.3		$31.0

Schedule of Deferred Tax Assets and Liabilities

The deferred tax (assets) and liabilities included on the balance sheets at December 31 arise from the following temporary differences (in millions):

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
Alliant Energy	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$2,762.9		$2,762.9			$—			$2,627.8		$2,627.8
Investment in ATC	—			138.1		138.1			—			131.6		131.6
Net operating losses carryforwards - state	(38.3		)	—		(38.3		)	(45.7		)	—		(45.7		)
Regulatory liability - IPL’s tax benefit riders	(66.1		)	—		(66.1		)	(100.9		)	—		(100.9		)
Federal credit carryforwards	(236.4		)	—		(236.4		)	(201.0		)	—		(201.0		)
Net operating losses carryforwards - federal	(250.9		)	—		(250.9		)	(332.8		)	—		(332.8		)
Other	(85.4		)	157.3		71.9			(88.1		)	180.1		92.0
		($677.1	)		$3,058.3		$2,381.2			($768.5	)		$2,939.5		$2,171.0

	2015		2014
Current deferred tax assets	N/A			($150.1	)
Non-current deferred tax liabilities		$2,381.2	2,321.1
Total net deferred tax liabilities		$2,381.2		$2,171.0

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
IPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,587.8		$1,587.8			$—			$1,545.1		$1,545.1
Regulatory liability - tax benefit riders	(66.1		)	—		(66.1		)	(100.9		)	—		(100.9		)
Federal credit carryforwards	(81.7		)	—		(81.7		)	(66.5		)	—		(66.5		)
Net operating losses carryforwards - federal	(113.1		)	—		(113.1		)	(157.8		)	—		(157.8		)
Other	(36.7		)	87.8		51.1			(37.1		)	83.5		46.4
		($297.6	)		$1,675.6		$1,378.0			($362.3	)		$1,628.6		$1,266.3

	2015		2014
Current deferred tax assets	N/A			($104.0	)
Non-current deferred tax liabilities		$1,378.0	1,370.3
Total net deferred tax liabilities		$1,378.0		$1,266.3

	2015								2014
	Deferred			Deferred Tax					Deferred			Deferred Tax
WPL	Tax Assets			Liabilities		Net			Tax Assets			Liabilities		Net
Property		$—			$1,027.0		$1,027.0			$—			$963.0		$963.0
Investment in ATC	—			138.9		138.9			—			132.1		132.1
Federal credit carryforwards	(95.5		)	—		(95.5		)	(76.7		)	—		(76.7		)
Net operating losses carryforwards - federal	(105.1		)	—		(105.1		)	(131.6		)	—		(131.6		)
Other	(27.8		)	67.9		40.1			(37.1		)	79.7		42.6
		($228.4	)		$1,233.8		$1,005.4			($245.4	)		$1,174.8		$929.4

	2015		2014
Current deferred tax assets	N/A			($37.7	)
Non-current deferred tax liabilities		$1,005.4	967.1
Total net deferred tax liabilities		$1,005.4		$929.4

Summary Of Tax Credit Carryforwards

At December 31, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (in millions):

		Alliant Energy				IPL				WPL
	Earliest	Tax		Deferred		Tax		Deferred		Tax		Deferred
	Expiration Date	Carryforwards		Tax Assets		Carryforwards		Tax Assets		Carryforwards		Tax Assets
Federal net operating losses	2030		$732		$251		$336		$113		$300		$105
State net operating losses	2018	766		38		20		1		76		4
Federal tax credits	2022	240		236		85		82		96		96
					$525				$196				$205

Schedule Of Open Tax Years

Open tax years - Tax years that remain subject to the statute of limitations in the major jurisdictions for each of Alliant Energy, IPL and WPL are as follows:

Consolidated federal income tax returns (a)	2012	-	2014
Consolidated Iowa income tax returns (b)	2012	-	2014
Wisconsin combined tax returns (c)	2011	-	2014

(a) These 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 these federal tax returns expires three years from each filing date.

(b) The statute of limitations for these Iowa tax returns expires three years from each filing date.

(c) The statute of limitations for these Wisconsin combined tax returns expires four years from each filing date.