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 27, 2005

Commission File Number	Exact Name of Registrant as Specified in Charter; State of Incorporation; Address and Telephone Number	IRS Employer Identification Number
1-14756	Ameren Corporation (Missouri Corporation) 1901 Chouteau Avenue St. Louis, Missouri 63103 (314) 621-3222	43-1723446
1-3672	Central Illinois Public Service Company (Illinois Corporation) 607 East Adams Street Springfield, Illinois 62739 (217) 523-3600	37-0211380
2-95569	CILCORP Inc. (Illinois Corporation) 300 Liberty Street Peoria, Illinois 61602 (309) 677-5271	37-1169387
1-2732	Central Illinois Light Company (Illinois Corporation) 300 Liberty Street Peoria, Illinois 61602 (309) 677-5271	37-0211050
1-3004	Illinois Power Company (Illinois Corporation) 370 South Main Street Decatur, Illinois 62523 (217) 424-6600	37-0344645

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))

SECTION 8 - OTHER EVENTS

ITEM 8.01 Other Events.

On December 27, 2005, Central Illinois Light Company, doing business as AmerenCILCO, Central Illinois Public Service Company, doing business as AmerenCIPS, and Illinois Power Company, doing business as AmerenIP, issued a press release announcing that they had filed requests with the Illinois Commerce Commission for increases in electricity delivery service rates. The press release is attached as Exhibit 99.1 and is incorporated herein by reference.

SECTION 9 - FINANCIAL STATEMENTS AND EXHIBITS

ITEM 9.01 Financial Statements and Exhibits.

(d) Exhibits

   Exhibit Number:                 Title:

99.1   Press release, dated December 27, 2005.

This combined Form 8-K is being filed separately by Ameren Corporation, Central Illinois Public Service Company, CILCORP Inc., Central Illinois Light Company and Illinois Power Company (each a “registrant”). Information contained herein relating to any individual registrant has been filed by such registrant on its own behalf. No registrant makes any representation as to information relating to any other registrant.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. The signature for each undersigned company shall be deemed to relate only to matters having reference to such company or its subsidiaries.

AMEREN CORPORATION (Registrant)
	/s/ Martin J. Lyons
	Martin J. Lyons
	Vice President and Controller (Principal Accounting Officer)

CENTRAL ILLINOIS PUBLIC SERVICE COMPANY (Registrant)
	/s/ Martin J. Lyons
	Martin J. Lyons
	Vice President and Controller (Principal Accounting Officer)

CILCORP Inc. (Registrant)
	/s/ Martin J. Lyons
	Martin J. Lyons
	Vice President and Controller (Principal Accounting Officer)

CENTRAL ILLINOIS LIGHT COMPANY (Registrant)
	/s/ Martin J. Lyons
	Martin J. Lyons
	Vice President and Controller (Principal Accounting Officer)

ILLINOIS POWER COMPANY (Registrant)
	/s/ Martin J. Lyons
	Martin J. Lyons
	Vice President and Controller (Principal Accounting Officer)

Date: December 27, 2005

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Exhibit Index

Exhibit Number:Title:

99.1   Press release, dated December 27, 2005.

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