Regulatory Matters

6 Months Ended

Jun. 30, 2018

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

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

	Alliant Energy				IPL				WPL
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
Tax-related		$776.0		$778.2		$742.2		$750.5		$33.8		$27.7
Pension and OPEB costs	529.2		548.0		265.6		274.4		263.6		273.6
Asset retirement obligations	109.8		109.3		76.3		72.5		33.5		36.8
EGUs retired early	91.2		63.8		60.2		31.6		31.0		32.2
Derivatives	49.4		45.3		27.9		21.8		21.5		23.5
Emission allowances	24.9		25.5		24.9		25.5		—		—
Other	97.9		96.6		52.1		55.3		45.8		41.3
		$1,678.4		$1,666.7		$1,249.2		$1,231.6		$429.2		$435.1

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

	Alliant Energy				IPL				WPL
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
Tax-related		$908.4		$899.4		$406.8		$399.5		$501.6		$499.9
Cost of removal obligations	402.4		410.0		274.9		274.5		127.5		135.5
Electric transmission cost recovery	105.6		90.4		41.1		26.4		64.5		64.0
Commodity cost recovery	25.7		21.0		20.4		14.6		5.3		6.4
IPL’s tax benefit riders	19.8		25.0		19.8		25.0		—		—
Other	51.0		51.4		11.8		15.4		39.2		36.0
		$1,512.9		$1,497.2		$774.8		$755.4		$738.1		$741.8

Tax-related- During the six months ended June 30, 2018, Alliant Energy’s and IPL’s tax-related regulatory assets decreased primarily due to the impacts of Iowa tax reform. In May 2018, Iowa tax reform was enacted, resulting in a reduction in the Iowa income tax rate from 12% to 9.8%, effective January 1, 2021 and the elimination of the deduction for federal income taxes, effective January 1, 2022. Alliant Energy’s and IPL’s deferred tax assets and liabilities as of June 30, 2018 were remeasured based upon the new tax rate. Alliant Energy and IPL recorded the net changes from remeasuring deferred tax assets and liabilities as a change in regulatory assets or regulatory liabilities. During the six months ended June 30, 2018, as a result of Iowa tax reform, Alliant Energy’s and IPL’s tax-related regulatory assets decreased $33.7 million and tax-related regulatory liabilities increased $7.3 million.

Partially offsetting the decrease to tax-related regulatory assets from Iowa tax reform discussed above was an increase in property-related differences for qualifying repairs expenditures. Alliant Energy’s and IPL’s tax-related regulatory assets are generally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles. Deferred tax amounts for such property-related differences at IPL are recorded to regulatory assets, along with the necessary revenue requirement tax gross-ups.

Electric generating units retired early - In June 2018, IPL retired the M.L. Kapp Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. The remaining net book value, which was $30 million as of June 30, 2018, is currently included in IPL’s rate base and IPL is earning a return of and a return on the outstanding balance. IPL expects continued recovery of the remaining net book value to be addressed in a future rate review.

Other - In January 2018, the IUB issued an order requiring IPL and other investor-owned utilities in Iowa to track all calculated differences since January 1, 2018 resulting from Federal Tax Reform, such that any over-collections can be refunded to its customers at a future date. Pursuant to IUB approval, the retail electric portion of IPL’s Federal Tax Reform benefits is currently being refunded to customers, beginning May 2018. In January 2018, the PSCW issued an order directing WPL and other investor-owned utilities in Wisconsin to defer the revenue requirement impacts resulting from Federal Tax Reform since its inception. Pursuant to PSCW approval, the retail electric and gas portions of WPL’s Federal Tax Reform benefits are currently being refunded to customers, beginning June 2018. As of June 30, 2018, Alliant Energy, IPL and WPL deferred $10 million, $7 million and $3 million, respectively, as a result of these orders related to Federal Tax Reform, which is included in “Other” in the regulatory liabilities table above, which was recorded as a reduction in revenues. For both the three and six months ended June 30, 2018, Alliant Energy, IPL, and WPL refunded Federal Tax Reform benefits of $27 million, $7 million, and $20 million, respectively.

In December 2016, WPL received an order from the PSCW related to its retail electric and gas rate review for the 2017/2018 Test Period. The order included provisions that require WPL to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels in 2018. As of June 30, 2018, Alliant Energy and WPL deferred $7 million of WPL’s 2018 earnings related to this provision, which is included in “Other” in the regulatory liabilities table above.

Utility Rate Reviews -

IPL’s Retail Gas Rate Review (2017 Test Year) - In May 2018, IPL filed a request with the IUB to increase annual gas base rates for its Iowa retail gas customers by $20 million, or approximately 8%. The request was based on a 2017 historical Test Year as adjusted for certain known and measurable changes occurring up to 12 months after the commencement of the proceeding. The key drivers for the filing included recovery of capital projects, partially offset by the benefits of Federal Tax Reform. An interim retail gas rate increase of $11 million, or approximately 5%, on an annual basis, was implemented effective May 14, 2018. The interim rate increase does not require regulatory approval; however, it will be subject to refund pending determination of final rates. IPL currently expects a decision from the IUB in 2019 with final rates effective by the second quarter of 2019. The IUB must issue a decision on requests for retail rate changes within 10 months from the date the application is filed.

IPL’s Retail Electric Rate Review (2016 Test Year) - In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers. An interim retail electric base rate increase of $102 million, or approximately 7%, on an annual basis, was implemented effective April 13, 2017. In September 2017, IPL reached a settlement agreement with intervener groups for an annual electric base rate increase of $130 million, or approximately 9%. In February 2018, the IUB issued an order approving the settlement. Final rates were effective May 1, 2018. For the three and six months ended June 30, 2018 compared to the same periods in 2017, Alliant Energy and IPL recorded increases in electric base rates of $5 million and $28 million, respectively, in conjunction with the interim and final retail electric base rate increases.

WPL’s Retail Electric and Gas Rate Review (2019/2020 Test Period) - In August 2018, the PSCW issued a decision approving WPL’s proposed settlement for its retail electric and gas rate review covering the 2019/2020 Test Period, which was based on a stipulated agreement between WPL and intervener groups. Under the settlement, WPL retail electric and gas base rates will not change through the end of 2020.

IPL [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

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

	Alliant Energy				IPL				WPL
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
Tax-related		$776.0		$778.2		$742.2		$750.5		$33.8		$27.7
Pension and OPEB costs	529.2		548.0		265.6		274.4		263.6		273.6
Asset retirement obligations	109.8		109.3		76.3		72.5		33.5		36.8
EGUs retired early	91.2		63.8		60.2		31.6		31.0		32.2
Derivatives	49.4		45.3		27.9		21.8		21.5		23.5
Emission allowances	24.9		25.5		24.9		25.5		—		—
Other	97.9		96.6		52.1		55.3		45.8		41.3
		$1,678.4		$1,666.7		$1,249.2		$1,231.6		$429.2		$435.1

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

	Alliant Energy				IPL				WPL
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
Tax-related		$908.4		$899.4		$406.8		$399.5		$501.6		$499.9
Cost of removal obligations	402.4		410.0		274.9		274.5		127.5		135.5
Electric transmission cost recovery	105.6		90.4		41.1		26.4		64.5		64.0
Commodity cost recovery	25.7		21.0		20.4		14.6		5.3		6.4
IPL’s tax benefit riders	19.8		25.0		19.8		25.0		—		—
Other	51.0		51.4		11.8		15.4		39.2		36.0
		$1,512.9		$1,497.2		$774.8		$755.4		$738.1		$741.8

Tax-related- During the six months ended June 30, 2018, Alliant Energy’s and IPL’s tax-related regulatory assets decreased primarily due to the impacts of Iowa tax reform. In May 2018, Iowa tax reform was enacted, resulting in a reduction in the Iowa income tax rate from 12% to 9.8%, effective January 1, 2021 and the elimination of the deduction for federal income taxes, effective January 1, 2022. Alliant Energy’s and IPL’s deferred tax assets and liabilities as of June 30, 2018 were remeasured based upon the new tax rate. Alliant Energy and IPL recorded the net changes from remeasuring deferred tax assets and liabilities as a change in regulatory assets or regulatory liabilities. During the six months ended June 30, 2018, as a result of Iowa tax reform, Alliant Energy’s and IPL’s tax-related regulatory assets decreased $33.7 million and tax-related regulatory liabilities increased $7.3 million.

Partially offsetting the decrease to tax-related regulatory assets from Iowa tax reform discussed above was an increase in property-related differences for qualifying repairs expenditures. Alliant Energy’s and IPL’s tax-related regulatory assets are generally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles. Deferred tax amounts for such property-related differences at IPL are recorded to regulatory assets, along with the necessary revenue requirement tax gross-ups.

Electric generating units retired early - In June 2018, IPL retired the M.L. Kapp Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. The remaining net book value, which was $30 million as of June 30, 2018, is currently included in IPL’s rate base and IPL is earning a return of and a return on the outstanding balance. IPL expects continued recovery of the remaining net book value to be addressed in a future rate review.

Other - In January 2018, the IUB issued an order requiring IPL and other investor-owned utilities in Iowa to track all calculated differences since January 1, 2018 resulting from Federal Tax Reform, such that any over-collections can be refunded to its customers at a future date. Pursuant to IUB approval, the retail electric portion of IPL’s Federal Tax Reform benefits is currently being refunded to customers, beginning May 2018. In January 2018, the PSCW issued an order directing WPL and other investor-owned utilities in Wisconsin to defer the revenue requirement impacts resulting from Federal Tax Reform since its inception. Pursuant to PSCW approval, the retail electric and gas portions of WPL’s Federal Tax Reform benefits are currently being refunded to customers, beginning June 2018. As of June 30, 2018, Alliant Energy, IPL and WPL deferred $10 million, $7 million and $3 million, respectively, as a result of these orders related to Federal Tax Reform, which is included in “Other” in the regulatory liabilities table above, which was recorded as a reduction in revenues. For both the three and six months ended June 30, 2018, Alliant Energy, IPL, and WPL refunded Federal Tax Reform benefits of $27 million, $7 million, and $20 million, respectively.

In December 2016, WPL received an order from the PSCW related to its retail electric and gas rate review for the 2017/2018 Test Period. The order included provisions that require WPL to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels in 2018. As of June 30, 2018, Alliant Energy and WPL deferred $7 million of WPL’s 2018 earnings related to this provision, which is included in “Other” in the regulatory liabilities table above.

Utility Rate Reviews -

IPL’s Retail Gas Rate Review (2017 Test Year) - In May 2018, IPL filed a request with the IUB to increase annual gas base rates for its Iowa retail gas customers by $20 million, or approximately 8%. The request was based on a 2017 historical Test Year as adjusted for certain known and measurable changes occurring up to 12 months after the commencement of the proceeding. The key drivers for the filing included recovery of capital projects, partially offset by the benefits of Federal Tax Reform. An interim retail gas rate increase of $11 million, or approximately 5%, on an annual basis, was implemented effective May 14, 2018. The interim rate increase does not require regulatory approval; however, it will be subject to refund pending determination of final rates. IPL currently expects a decision from the IUB in 2019 with final rates effective by the second quarter of 2019. The IUB must issue a decision on requests for retail rate changes within 10 months from the date the application is filed.

IPL’s Retail Electric Rate Review (2016 Test Year) - In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers. An interim retail electric base rate increase of $102 million, or approximately 7%, on an annual basis, was implemented effective April 13, 2017. In September 2017, IPL reached a settlement agreement with intervener groups for an annual electric base rate increase of $130 million, or approximately 9%. In February 2018, the IUB issued an order approving the settlement. Final rates were effective May 1, 2018. For the three and six months ended June 30, 2018 compared to the same periods in 2017, Alliant Energy and IPL recorded increases in electric base rates of $5 million and $28 million, respectively, in conjunction with the interim and final retail electric base rate increases.

WPL’s Retail Electric and Gas Rate Review (2019/2020 Test Period) - In August 2018, the PSCW issued a decision approving WPL’s proposed settlement for its retail electric and gas rate review covering the 2019/2020 Test Period, which was based on a stipulated agreement between WPL and intervener groups. Under the settlement, WPL retail electric and gas base rates will not change through the end of 2020.

WPL [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory Matters

REGULATORY MATTERS

Regulatory Assets and Regulatory Liabilities -

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

	Alliant Energy				IPL				WPL
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
Tax-related		$776.0		$778.2		$742.2		$750.5		$33.8		$27.7
Pension and OPEB costs	529.2		548.0		265.6		274.4		263.6		273.6
Asset retirement obligations	109.8		109.3		76.3		72.5		33.5		36.8
EGUs retired early	91.2		63.8		60.2		31.6		31.0		32.2
Derivatives	49.4		45.3		27.9		21.8		21.5		23.5
Emission allowances	24.9		25.5		24.9		25.5		—		—
Other	97.9		96.6		52.1		55.3		45.8		41.3
		$1,678.4		$1,666.7		$1,249.2		$1,231.6		$429.2		$435.1

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

	Alliant Energy				IPL				WPL
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
Tax-related		$908.4		$899.4		$406.8		$399.5		$501.6		$499.9
Cost of removal obligations	402.4		410.0		274.9		274.5		127.5		135.5
Electric transmission cost recovery	105.6		90.4		41.1		26.4		64.5		64.0
Commodity cost recovery	25.7		21.0		20.4		14.6		5.3		6.4
IPL’s tax benefit riders	19.8		25.0		19.8		25.0		—		—
Other	51.0		51.4		11.8		15.4		39.2		36.0
		$1,512.9		$1,497.2		$774.8		$755.4		$738.1		$741.8

Tax-related- During the six months ended June 30, 2018, Alliant Energy’s and IPL’s tax-related regulatory assets decreased primarily due to the impacts of Iowa tax reform. In May 2018, Iowa tax reform was enacted, resulting in a reduction in the Iowa income tax rate from 12% to 9.8%, effective January 1, 2021 and the elimination of the deduction for federal income taxes, effective January 1, 2022. Alliant Energy’s and IPL’s deferred tax assets and liabilities as of June 30, 2018 were remeasured based upon the new tax rate. Alliant Energy and IPL recorded the net changes from remeasuring deferred tax assets and liabilities as a change in regulatory assets or regulatory liabilities. During the six months ended June 30, 2018, as a result of Iowa tax reform, Alliant Energy’s and IPL’s tax-related regulatory assets decreased $33.7 million and tax-related regulatory liabilities increased $7.3 million.

Partially offsetting the decrease to tax-related regulatory assets from Iowa tax reform discussed above was an increase in property-related differences for qualifying repairs expenditures. Alliant Energy’s and IPL’s tax-related regulatory assets are generally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles. Deferred tax amounts for such property-related differences at IPL are recorded to regulatory assets, along with the necessary revenue requirement tax gross-ups.

Electric generating units retired early - In June 2018, IPL retired the M.L. Kapp Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. The remaining net book value, which was $30 million as of June 30, 2018, is currently included in IPL’s rate base and IPL is earning a return of and a return on the outstanding balance. IPL expects continued recovery of the remaining net book value to be addressed in a future rate review.

Other - In January 2018, the IUB issued an order requiring IPL and other investor-owned utilities in Iowa to track all calculated differences since January 1, 2018 resulting from Federal Tax Reform, such that any over-collections can be refunded to its customers at a future date. Pursuant to IUB approval, the retail electric portion of IPL’s Federal Tax Reform benefits is currently being refunded to customers, beginning May 2018. In January 2018, the PSCW issued an order directing WPL and other investor-owned utilities in Wisconsin to defer the revenue requirement impacts resulting from Federal Tax Reform since its inception. Pursuant to PSCW approval, the retail electric and gas portions of WPL’s Federal Tax Reform benefits are currently being refunded to customers, beginning June 2018. As of June 30, 2018, Alliant Energy, IPL and WPL deferred $10 million, $7 million and $3 million, respectively, as a result of these orders related to Federal Tax Reform, which is included in “Other” in the regulatory liabilities table above, which was recorded as a reduction in revenues. For both the three and six months ended June 30, 2018, Alliant Energy, IPL, and WPL refunded Federal Tax Reform benefits of $27 million, $7 million, and $20 million, respectively.

In December 2016, WPL received an order from the PSCW related to its retail electric and gas rate review for the 2017/2018 Test Period. The order included provisions that require WPL to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels in 2018. As of June 30, 2018, Alliant Energy and WPL deferred $7 million of WPL’s 2018 earnings related to this provision, which is included in “Other” in the regulatory liabilities table above.

Utility Rate Reviews -

IPL’s Retail Gas Rate Review (2017 Test Year) - In May 2018, IPL filed a request with the IUB to increase annual gas base rates for its Iowa retail gas customers by $20 million, or approximately 8%. The request was based on a 2017 historical Test Year as adjusted for certain known and measurable changes occurring up to 12 months after the commencement of the proceeding. The key drivers for the filing included recovery of capital projects, partially offset by the benefits of Federal Tax Reform. An interim retail gas rate increase of $11 million, or approximately 5%, on an annual basis, was implemented effective May 14, 2018. The interim rate increase does not require regulatory approval; however, it will be subject to refund pending determination of final rates. IPL currently expects a decision from the IUB in 2019 with final rates effective by the second quarter of 2019. The IUB must issue a decision on requests for retail rate changes within 10 months from the date the application is filed.

IPL’s Retail Electric Rate Review (2016 Test Year) - In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers. An interim retail electric base rate increase of $102 million, or approximately 7%, on an annual basis, was implemented effective April 13, 2017. In September 2017, IPL reached a settlement agreement with intervener groups for an annual electric base rate increase of $130 million, or approximately 9%. In February 2018, the IUB issued an order approving the settlement. Final rates were effective May 1, 2018. For the three and six months ended June 30, 2018 compared to the same periods in 2017, Alliant Energy and IPL recorded increases in electric base rates of $5 million and $28 million, respectively, in conjunction with the interim and final retail electric base rate increases.

WPL’s Retail Electric and Gas Rate Review (2019/2020 Test Period) - In August 2018, the PSCW issued a decision approving WPL’s proposed settlement for its retail electric and gas rate review covering the 2019/2020 Test Period, which was based on a stipulated agreement between WPL and intervener groups. Under the settlement, WPL retail electric and gas base rates will not change through the end of 2020.