8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 20, 2007

Alliant Energy Corporation
(Exact name of registrant as specified in its charter)

Wisconsin	1-9894	39-1380265
(State or other jurisdiction	(Commission	(IRS Employer
of incorporation)	File Number)	Identification No.)

4902 North Biltmore Lane, Madison, Wisconsin	53718
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code (608) 458-3311

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[   ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

[   ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

[   ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

[   ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 2.01 Completion of Acquisition or Disposition of Assets.

        On December 20, 2007, Interstate Power and Light Company (“IPL”), a subsidiary of Alliant Energy Corporation (the “Company”), completed the previously announced sale (the “Divestiture”) of its electric transmission assets to ITC Midwest LLC (“ITC Midwest”). The Divestiture was effected pursuant to the terms of an Asset Sale Agreement, dated as of January 18, 2007, by and between IPL and ITC Midwest (the “ASA”). ITC Midwest is a wholly-owned subsidiary of ITC Holdings Corp.

        Under the terms of the ASA, ITC Midwest acquired IPL’s transmission assets at 34.5-kilovolts and higher located in Iowa, Minnesota and Illinois, including transmission lines, transmission substations, land rights, contracts, permits and equipment. The cash purchase price for the assets sold by IPL in the Divestiture was $783.1 million. The purchase price is subject to several post-closing adjustments as described in the ASA. In addition to the cash purchase price and as part of the Divestiture, ITC Midwest assumed specified liabilities relating to IPL’s transmission assets and transmission business.

        The foregoing description of the Divestiture is qualified in its entirety by reference to the ASA, a copy of which is incorporated by reference as Exhibit 2.1 hereto, and incorporated by reference herein. There are representations and warranties contained in the ASA that were made by the parties to each other as of specific dates. The assertions embodied in these representations and warranties were made solely for purposes of the ASA and may be subject to important qualifications and limitations agreed to by the parties in connection with negotiating its terms. Moreover, certain representations and warranties may not be accurate or complete as of any specified date because they are subject to a contractual standard of materiality that is different from certain standards generally applicable to shareowners or were used for the purpose of allocating risk between the parties rather than establishing matters as facts. Based upon the foregoing reasons, no person should rely on the representations and warranties as statements of factual information.

        The required pro forma condensed consolidated financial information of the Company giving effect to the Divestiture is attached to this Current Report on Form 8-K as Exhibit 99.1.

Item 9.01 Financial Statements and Exhibits.

(a) Not applicable.

(b) Pro Forma Financial Information. Included in Exhibit 99.1 to this Current Report on Form 8-K is the following unaudited pro forma condensed consolidated financial information of the Company giving effect to the Divestiture:

1. Unaudited Pro Forma Condensed Consolidated Balance Sheet of the Company as of September 30, 2007.

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2. Unaudited Pro Forma Condensed Consolidated Statements of Income of the Company for the Nine Months Ended September 30, 2007 and Year Ended December 31, 2006.

3. Notes to Unaudited Pro Forma Condensed Consolidated Financial Information.

(c) Not applicable.

(d) Exhibits. The following exhibits are being filed herewith:

(2.1) Asset Sale Agreement, dated as of January 18, 2007, by and between Interstate Power and Light Company and ITC Midwest LLC [incorporated by reference to Exhibit 2.1 to the Company’s Current Report on Form 8-K dated January 18, 2007]

(99.1) Unaudited Pro Forma Condensed Consolidated Financial Information of the Company reflecting the Divestiture

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SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date:  December 21, 2007	ALLIANT ENERGY CORPORATION
	By:  /s/ Thomas L. Hanson
	Thomas L. Hanson
	Vice President-Controller and
	Chief Accounting Officer

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ALLIANT ENERGY CORPORATION

Exhibit Index to Current Report on Form 8-K
Dated December 20, 2007

Exhibit Number

(2.1) Asset Sale Agreement, dated as of January 18, 2007, by and between Interstate Power and Light Company and ITC Midwest LLC* [incorporated by reference to Exhibit 2.1 to the Company’s Current Report on Form 8-K dated January 18, 2007]

(99.1) Unaudited Pro Forma Condensed Consolidated Financial Information of the Company reflecting the Divestiture

* All schedules and exhibits to this Exhibit have been omitted pursuant to Item 601(b)(2) of Regulation S-K. The Company agrees to furnish supplementally a copy of any omitted schedules and exhibits to the Securities and Exchange Commission upon request.

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EX-99.1

EXHIBIT 99.1

ALLIANT ENERGY CORPORATION
UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL INFORMATION

The following unaudited pro forma condensed consolidated balance sheet as of September 30, 2007 and the unaudited pro forma condensed consolidated statements of income for the nine months ended September 30, 2007 and the year ended December 31, 2006 give effect to the sale (the Divestiture) by Interstate Power and Light Company (IPL), a subsidiary of Alliant Energy Corporation (Alliant Energy), of its electric transmission assets to ITC Midwest LLC (ITC) pursuant to the terms of an Asset Sale Agreement, dated as of January 18, 2007, by and between IPL and ITC (the Sale Agreement). The pro forma condensed consolidated financial information should be read in conjunction with the historical financial statements and related notes thereto of Alliant Energy contained in its combined Annual Report on Form 10-K for the year ended December 31, 2006 and its combined Quarterly Report on Form 10-Q for the quarter ended September 30, 2007.

The pro forma condensed consolidated financial information is presented for information purposes only, is based on the assumptions set forth below, includes various estimates and is not necessarily indicative of Alliant Energy’s financial results had the Divestiture actually occurred on the dates assumed nor is it necessarily indicative of Alliant Energy’s future results of operations.

ALLIANT ENERGY CORPORATION
UNAUDITED PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET
(in millions)

	Historical		Pro Forma Adjustments			Pro Forma
ASSETS	September 30, 2007
Property, plant and equipment, net	$	5,089.5	$	(500.3	)(b)	$	4,589.2
Cash and cash equivalents		108.1		579.1	(a)		687.2
Other current assets		741.8		50.0	(a)		788.5
				(3.3	)(b)
Investments		234.5		--			234.5
Other assets		753.3		(1.0	)(b)		752.3
Total assets	$	6,927.2	$	124.5		$	7,051.7
CAPITALIZATION AND LIABILITIES
Common equity	$	2,511.8	$	128.2	(c)	$	2,640.0
Cumulative preferred stock of subsidiaries, net		243.8		--			243.8
Long-term debt, net (excluding current portion)		1,593.9		--			1,593.9
Total capitalization		4,349.5		128.2			4,477.7
Current liabilities		754.3		(133.4	)(a)		648.0
				(4.7	)(b)
				31.8	(c)
Deferred income taxes		770.8		58.7	(c)		829.5
Long-term regulatory liabilities		618.6		(44.1	)(b)		663.2
				88.7	(d)
Other long-term liabilities and deferred credits		434.0		(0.7	)(b)		433.3
Total liabilities		2,577.7		(3.7	)		2,574.0
Total capitalization and liabilities	$	6,927.2	$	124.5		$	7,051.7

Refer to accompanying Notes to Unaudited Pro Forma Condensed Consolidated Financial Information.

ALLIANT ENERGY CORPORATION
UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF INCOME
(dollars in millions, except per share amounts)

	Historical			Pro Forma Adjustments			Pro Forma
	Nine Months Ended September 30, 2007
Operating revenues	$	2,566.2			($ 9.3	)(e)	$	2,556.9
Operating expenses:
Electric production fuel and purchased power		917.0			--			917.0
Cost of gas sold		304.5			--			304.5
Other operation and maintenance		644.4			(12.5	)(f)		685.0
					58.1	(h)
					(5.0)	(i)
Depreciation and amortization		197.3			(11.5	)(f)		185.8
Taxes other than income taxes		81.6			(5.1	)(f)		76.5
Total operating expenses		2,144.8			24.0			2,168.8
Operating income		421.4			(33.3	)		388.1
Interest expense		86.3			(3.0	)(i)		85.9
					2.6	(j)
Other income, net:
Equity income from unconsolidated investments		(21.7	)		--			(21.7	)
Other income, net		(4.5	)		0.9	(g)		(3.6	)
Total other income, net		(26.2	)		0.9			(25.3	)
Income from continuing operations before income taxes		361.3			(33.8	)		327.5
Income taxes		134.9			(14.0	)(k)		120.9
Income from continuing operations	$	226.4			($ 19.8	)	$	206.6
Weighted average number of common shares outstanding (000s):
Basic		113,026			113,026			113,026
Diluted		113,279			113,279			113,279
Earnings per weighted average common share from continuing operations:
Basic	$	2.00			($ 0.18	)	$	1.83
Diluted	$	2.00			($ 0.17	)	$	1.82
	Year Ended December 31, 2006
Operating revenues	$	3,359.4		$	(12.4	)(e)	$	3,347.0
Operating expenses:
Electric production fuel and purchased power		1,257.4			--			1,257.4
Cost of gas sold		431.7			--			431.7
Other operation and maintenance		807.2			(11.1	)(f)		869.3
					77.4	(h)
					(4.2	)(i)
Depreciation and amortization		261.4			(14.6	)(f)		246.8
Taxes other than income taxes		108.2			(6.5	)(f)		101.7
Total operating expenses		2,865.9			41.0			2,906.9
Operating income		493.5			(53.4	)		440.1
Interest expense		145.7			(1.8	)(i)		147.4
					3.5	(j)
Other (income) expense, net:
Gain on sale of Alliant Energy New Zealand Ltd. stock		(253.9	)		--			(253.9	)
Equity income from unconsolidated investments		(45.5	)		--			(45.5	)
Loss on early extinguishment of debt		90.8			--			90.8
Other expense, net		15.1			1.4	(g)		16.5
Total other income, net		(193.5	)		1.4			(192.1	)
Income from continuing operations before income taxes		541.3			(56.5	)		484.8
Income taxes		203.0			(23.4	)(k)		179.6
Income from continuing operations	$	338.3		$	(33.1	)	$	305.2
Weighted average number of common shares outstanding (000s):
Basic		116,826			116,826			116,826
Diluted		117,190			117,190			117,190
Earnings per weighted average common share from continuing operations:
Basic	$	2.90		$	(0.28	)	$	2.61
Diluted	$	2.89		$	(0.28	)	$	2.60

Refer to accompanying Notes to Unaudited Pro Forma Condensed Consolidated Financial Information.

ALLIANT ENERGY CORPORATION
NOTES TO UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL INFORMATION

The unaudited pro forma condensed consolidated balance sheet assumes that the Divestiture occurred as of the balance sheet date (September 30, 2007) and reflects the following adjustments (in millions):

(a) Proceeds — Adjustment to record the net cash proceeds that IPL would have received based on an assumed closing date of September 30, 2007. The gross sales price of $754 million reflected in the Sale Agreement was subject to adjustments at closing based on the value of the net assets transferred as of the closing date. The net cash proceeds were also adjusted by the transaction costs directly related to the Divestiture. The pro forma financial statements assume IPL used a portion of the net cash proceeds to retire its commercial paper borrowings and financings from the sale of utility accounts receivable as of the closing date.

Net cash proceeds:
Gross sales price per Sale Agreement	$	754.0
Purchase price adjustments as of September 30, 2007		21.2
Assumed gross cash proceeds as of September 30, 2007		775.2	*
Less: Transaction costs as of September 30, 2007		12.7
Assumed net cash proceeds as of September 30, 2007		762.5
Use of proceeds:
Retire IPL’s commercial paper borrowings as of September 30, 2007		(133.4	)
Eliminate IPL’s financings from the sale of utility accounts receivable as of
September 30, 2007		(50.0	)
Remaining amount held in cash and cash equivalents	$	579.1

* Gross cash proceeds as of the closing date (December 20, 2007) were $783.1 million which is $8 million greater than the assumed gross cash proceeds identified above primarily due to estimated increases in the carrying value of net assets sold during the fourth quarter of 2007 prior to the sale.

(b) Assets and Liabilities Removed with Divestiture — Adjustments to remove the carrying value of the following assets and liabilities as of September 30, 2007 that have been transferred to ITC in connection with the Divestiture:

Property, plant and equipment, net (electric transmission assets sold)	$	500.3
Current assets (primarily materials and supplies sold)		3.3
Other assets		1.0
Current liabilities (primarily accrued capital expenditures assumed by ITC)		(4.7	)
Long-term regulatory liabilities (cost of removal obligations assumed by ITC)		(44.1	)
Other long-term liabilities		(0.7	)
Net carrying value of assets sold to and liabilities assumed by ITC	$	455.1

(c) Pro Forma Gain from Divestiture — Adjustments to record the pro forma gain and related income tax obligation from the Divestiture based on an assumed closing date of September 30, 2007. IPL expects to qualify to pay taxes related to the pro forma gain from the Divestiture over an eight-year period resulting in only a portion of the income tax obligation being current. The pro forma gain from Divestiture has been calculated as follows:

Net cash proceeds (note (a) above)	$	762.5
Less: Carrying value of assets and liabilities removed with the Divestiture (note (b) above)		455.1
Less: Long-term regulatory liability established with the Divestiture (note (d) below)		88.7
Pre-tax pro forma gain		218.7
Estimated income tax obligation of the pre-tax pro forma gain based on the estimated weighted
average statutory rates for all jurisdictions of 41.4% (current liability portion - $31.8 million)		90.5
Pro forma gain from Divestiture, net of tax	$	128.2

(d) Regulatory Treatment of Pro Forma Gain — Adjustment to record the present value of the estimated amounts to be refunded to IPL’s customers in accordance with regulatory approvals from various state commissions. IPL expects to refund to its customers aggregate payments of $13 million per year for eight years beginning in the year IPL’s customers first experience an increase in rates related to transmission charges assessed by buyer. Refer to note (c) above for additional discussion of the pro forma gain realized with respect to the Divestiture.

The unaudited pro forma condensed consolidated statements of income assume the Divestiture occurred as of the beginning of the earliest period presented (January 1, 2006) and reflect the following adjustments:

(e) Historical Operating Revenues — Adjustment to remove historical wheeling revenues directly related to the net assets eliminated with the Divestiture.

(f) Historical Operating Expenses — Adjustments to remove historical expenses directly related to the operation, maintenance, depreciation and property taxes of the net assets eliminated with the Divestiture.

(g) Historical Allowance for Funds Used During Construction (AFUDC) — Adjustment to remove historical AFUDC related to the assets eliminated with the Divestiture.

(h) Estimated Transmission Charges from Buyer — Adjustment to add estimated transmission charges from buyer for transmission services required to serve IPL’s customers.

(i) Historical Costs for Commercial Paper and Sale of Utility Accounts Receivable — Adjustments to remove historical interest expense from IPL’s commercial paper borrowings and historical costs from IPL’s utility accounts receivable sale program. The pro forma financial statements assume IPL used a portion of the proceeds from the Divestiture to retire outstanding commercial paper borrowings and eliminate financings from the sale of utility accounts receivable as of the closing date.

(j) Estimated Interest Expense on Long-term Regulatory Liability — Adjustment to add the estimated interest expense related to the long-term regulatory liability established with the Divestiture. Refer to note (d) above for additional details.

(k) Income Tax Expense Impacts — Adjustment to estimate the income tax expense impacts of the pre-tax pro forma adjustments based on the estimated weighted average statutory rates for all jurisdictions of 41.4%.