Exhibit 12.3

Central Illinois Public Service Company

Computation of Ratios of Earnings to Fixed Charges and Combined

Fixed Charges and Preferred Stock Dividend Requirements

(Thousands of Dollars, Except Ratios)



|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|------------------------------------------------------------------------------------- |  | ----------------------- | ------- | ---- | - | ------ |  | ---- | ------ | ---- | - | ------ |  | - | ------
|                                                                                      |  | Year Ended December 31,
|                                                                                      |  | 2001                    |         | 2002 |   | 2003   |  | 2004 |        | 2005
|Net income from continuing operations                                                 |  | $                       | 45,309  |      | $ | 26,355 |  | $    | 28,474 |      | $ | 32,463 |  | $ | 42,998
|Less- Change in accounting principle                                                  |  |                         | -       |      |   | -      |  |      | -      |      |   | -      |  |   | -     
|Less- Income from equity investee                                                     |  |                         | -       |      |   | -      |  |      | -      |      |   | -      |  |   | -     
|Add- Taxes based on income                                                            |  |                         | 28,245  |      |   | 16,955 |  |      | 6,245  |      |   | 16,135 |  |   | 24,596
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Net income before income taxes                                                        |  |                         | 73,554  |      |   | 43,310 |  |      | 34,719 |      |   | 48,598 |  |   | 67,594
|                                                                                      |  |                         |         |      |  
|Add- fixed charges:                                                                   |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Interest on long term debt                                                            |  |                         | 38,273  |      |   | 39,603 |  |      | 33,118 |      |   | 31,372 |  |   | 28,969
|Estimated interest cost within rental expense                                         |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Amortization of net debt premium, discount, and expenses                              |  |                         | 993     |      |   | 1,076  |  |      | 935    |      |   | 903    |  |   | 953   
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Total fixed charges                                                                   |  |                         | 39,266  |      |   | 40,679 |  |      | 34,053 |      |   | 32,275 |  |   | 29,922
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Earnings available for fixed charges                                                  |  |                         | 112,820 |      |   | 83,989 |  |      | 68,772 |      |   | 80,873 |  |   | 97,516
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Ratio of earnings to fixed charges                                                    |  |                         | 2.87    |      |   | 2.06   |  |      | 2.01   |      |   | 2.50   |  |   | 3.25  
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Earnings required for combined fixed charges and preferred stock dividends:           |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Preferred stock dividends                                                             |  |                         | 3,627   |      |   | 3,158  |  |      | 2,973  |      |   | 2,512  |  |   | 2,512 
|Adjustment to pre-tax basis                                                           |  |                         | 2,260   |      |   | 2,031  |  |      | 651    |      |   | 1,248  |  |   | 1,437 
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|                                                                                      |  |                         | 5,887   |      |   | 5,189  |  |      | 3,624  |      |   | 3,760  |  |   | 3,949 
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Combined fixed charges and preferred stock dividend requirements                      |  | $                       | 45,153  |      | $ | 45,868 |  | $    | 37,677 |      | $ | 36,035 |  | $ | 33,871
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |       
|Ratio of earnings to combined fixed charges and preferred stock dividend requirements |  |                         | 2.49    |      |   | 1.83   |  |      | 1.82   |      |   | 2.24   |  |   | 2.87  
|                                                                                      |  |                         |         |      |   |        |  |      |        |      |   |        |  |   |