Income Taxes (Tables)

3 Months Ended

Mar. 31, 2014

Income Tax [Line Items]

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
Three Months Ended March 31	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(11.9	)	(12.8	)	(31.2	)	(37.3	)	—		—
Production tax credits	(6.7	)	(7.5	)	(8.3	)	(9.7	)	(6.4	)	(6.9	)
Effect of rate-making on property-related differences	(5.3	)	(5.0	)	(12.4	)	(14.0	)	(1.0	)	(0.3	)
Other items, net	4.6		3.0		4.7		2.0		4.8		4.2
Overall income tax rate	15.7	%	12.7	%	(12.2	%)	(24.0	%)	32.4	%	32.0	%

Production Tax Credits (Net Of State Tax Impacts)

For the three months ended March 31, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):

	End of Production	Nameplate	Production Tax Credits
	Tax Credit Generation	Capacity in MW	2014		2013
Cedar Ridge (WPL)	December 2018	68		$1.2		$1.2
Bent Tree - Phase I (WPL)	February 2021	201	4.2		3.5
Subtotal (WPL)			5.4		4.7
Whispering Willow - East (IPL)	December 2019	200	4.6		3.9
				$10.0		$8.6

Summary Of Tax Credit Carryforwards

At March 31, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$697		$239	2029
State net operating losses	681		34		2018
Federal tax credits	181		178		2022
				$451

IPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$303		$104	2029
State net operating losses	172		8		2018
Federal tax credits	59		58		2022
				$170

WPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$302		$103	2029
State net operating losses	96		5		2018
Federal tax credits	64		62		2022
				$170

IPL [Member]

Income Tax [Line Items]

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
Three Months Ended March 31	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(11.9	)	(12.8	)	(31.2	)	(37.3	)	—		—
Production tax credits	(6.7	)	(7.5	)	(8.3	)	(9.7	)	(6.4	)	(6.9	)
Effect of rate-making on property-related differences	(5.3	)	(5.0	)	(12.4	)	(14.0	)	(1.0	)	(0.3	)
Other items, net	4.6		3.0		4.7		2.0		4.8		4.2
Overall income tax rate	15.7	%	12.7	%	(12.2	%)	(24.0	%)	32.4	%	32.0	%

Production Tax Credits (Net Of State Tax Impacts)

For the three months ended March 31, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):

	End of Production	Nameplate	Production Tax Credits
	Tax Credit Generation	Capacity in MW	2014		2013
Cedar Ridge (WPL)	December 2018	68		$1.2		$1.2
Bent Tree - Phase I (WPL)	February 2021	201	4.2		3.5
Subtotal (WPL)			5.4		4.7
Whispering Willow - East (IPL)	December 2019	200	4.6		3.9
				$10.0		$8.6

Summary Of Tax Credit Carryforwards

At March 31, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$697		$239	2029
State net operating losses	681		34		2018
Federal tax credits	181		178		2022
				$451

IPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$303		$104	2029
State net operating losses	172		8		2018
Federal tax credits	59		58		2022
				$170

WPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$302		$103	2029
State net operating losses	96		5		2018
Federal tax credits	64		62		2022
				$170

WPL [Member]

Income Tax [Line Items]

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
Three Months Ended March 31	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(11.9	)	(12.8	)	(31.2	)	(37.3	)	—		—
Production tax credits	(6.7	)	(7.5	)	(8.3	)	(9.7	)	(6.4	)	(6.9	)
Effect of rate-making on property-related differences	(5.3	)	(5.0	)	(12.4	)	(14.0	)	(1.0	)	(0.3	)
Other items, net	4.6		3.0		4.7		2.0		4.8		4.2
Overall income tax rate	15.7	%	12.7	%	(12.2	%)	(24.0	%)	32.4	%	32.0	%

Production Tax Credits (Net Of State Tax Impacts)

For the three months ended March 31, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):

	End of Production	Nameplate	Production Tax Credits
	Tax Credit Generation	Capacity in MW	2014		2013
Cedar Ridge (WPL)	December 2018	68		$1.2		$1.2
Bent Tree - Phase I (WPL)	February 2021	201	4.2		3.5
Subtotal (WPL)			5.4		4.7
Whispering Willow - East (IPL)	December 2019	200	4.6		3.9
				$10.0		$8.6

Summary Of Tax Credit Carryforwards

At March 31, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$697		$239	2029
State net operating losses	681		34		2018
Federal tax credits	181		178		2022
				$451

IPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$303		$104	2029
State net operating losses	172		8		2018
Federal tax credits	59		58		2022
				$170

WPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$302		$103	2029
State net operating losses	96		5		2018
Federal tax credits	64		62		2022
				$170