# EDGAR Filing Document

**Accession Number:** 0000018654
**File Stem:** 0001104659-26-037793
**Filing Date:** 2026-3
**Character Count:** 5153
**Document Hash:** f33c62a5c4fbd4edc9f60a05608b1f4f
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-037793.hdr.sgml**: 20260331

**ACCESSION NUMBER**: 0001104659-26-037793

**CONFORMED SUBMISSION TYPE**: DEFA14C

**PUBLIC DOCUMENT COUNT**: 5

**FILED AS OF DATE**: 20260331

**DATE AS OF CHANGE**: 20260331

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Ameren Illinois Co
- **CENTRAL INDEX KEY:** 0000018654
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRIC & OTHER SERVICES COMBINED [4931]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 370211380
- **STATE OF INCORPORATION:** IL
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14C
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-03672
- **FILM NUMBER:** 26822366

**BUSINESS ADDRESS:**
- **STREET 1:** 10 RICHARD MARK WAY
- **CITY:** COLLINSVILLE
- **STATE:** IL
- **ZIP:** 62234
- **BUSINESS PHONE:** 618-343-8150

**MAIL ADDRESS:**
- **STREET 1:** 10 RICHARD MARK WAY
- **CITY:** COLLINSVILLE
- **STATE:** IL
- **ZIP:** 62234

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** CENTRAL ILLINOIS PUBLIC SERVICE CO
- **DATE OF NAME CHANGE:** 19920703

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549** 

**SCHEDULE 14C INFORMATION**

**Information Statement Pursuant to Section 14(c) of the**

**Securities Exchange Act of 1934**

**(Amendment No.)**

Check the appropriate box:

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|:---|:---|
| ◻ | Preliminary Information Statement |
| ◻ | Confidential, for Use of the Commission Only (as permitted by Rule 14c-5(d)(2)) |
| ◻ | Definitive Information Statement |
| ⌧ | Definitive Additional Materials |

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**Ameren Illinois Company**

**(Name of Registrant as Specified In Its Charter)**

Payment of Filing Fee (Check the appropriate box):

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| | |
|:---|:---|
| ⌧ | No fee required |
| ◻ | Fee paid previously with preliminary materials |
| ◻ | Fee computed on table in exhibit required by Item 25(b) of Schedule 14A (17 CFR 240.14a-101) per Item 1 of this Schedule and Exchange Act Rules 14c-5(g) and 0-11 |

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| &nbsp;&nbsp;![GRAPHIC](tm264219d3_defa14cimg001.jpg) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;V90837-P45782 AMEREN ILLINOIS COMPANY 10 RICHARD MARK WAY COLLINSVILLE, IL 62234 You are receiving this communication because you hold securities in the company listed above. They have released informational materials that are now available for your review. This notice provides instructions on how to access AMEREN ILLINOIS COMPANY materials for informational purposes only. We are not asking you for a proxy and you are requested to not send us a proxy. You may view the materials online at www.proxyvote.com, scan the QR Barcode on the reverse side, or easily request a paper or e-mail copy (see reverse side). Important Notice Regarding the Availability of Materials Meeting Information Meeting Type: Annual Meeting For holders as of: March 16, 2026 Date: May 14, 2026 Time: 10:00 a.m. CDT Location: The company will be hosting the meeting live via the Internet this year. To attend the meeting via the Internet please visit www.virtualshareholdermeeting.com/AEE2026 and be sure to have the information that is printed in the box marked by the arrow (located on the following page). Meeting live via the Internet - please visit www.virtualshareholdermeeting.com/AEE2026. XXXX XXXX XXXX XXXX See the reverse side for instructions on how to access materials. |

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| &nbsp;&nbsp;![GRAPHIC](tm264219d3_defa14cimg002.jpg) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;V90838-P45782 How to View Online: Visit: www.proxyvote.com, or scan the QR Barcode below. Have the information that is printed in the box marked by the arrow above. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these materials, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL\*: sendmaterial@proxyvote.com \* If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow above in the subject line. Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Materials Available to VIEW or RECEIVE: SCAN TO VIEW MATERIALS w ANNUAL REPORT INFORMATION STATEMENT How to Access the Materials |

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| &nbsp;&nbsp;![GRAPHIC](tm264219d3_defa14cimg003.jpg) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;V90839-P45782 THIS NOTICE WILL ENABLE YOU TO ACCESS MATERIALS FOR INFORMATIONAL PURPOSES ONLY |

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| &nbsp;&nbsp;![GRAPHIC](tm264219d3_defa14cimg004.jpg) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;V90840-P45782 THIS PAGE WAS INTENTIONALLY LEFT BLANK |

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