Exhibit (12)(a) ILLINOVA CORPORATION STATEMENT OF COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES (Thousands of Dollars) Year Ended December 31, Supplemental** Supplemental*** ------------------------------------------------------------------------------------- 1992 1993 1993 1994 1995 1996 1997 1997 ---- ---- ---- ---- ---- ---- ---- ---- Earnings Available for Fixed Charges: Net Income (Loss).................... $ 93,234 ($ 81,874) ($ 81,874) $ 151,786 $ 151,601 $ 191,021 ($ 90,553) ($ 90,553) Add: Income Taxes: Current ..................... 22,930 25,260 25,260 58,354 98,578 163,873 70,975 70,975 Deferred - Net............... 63,739 82,057 82,057 71,177 34,137 (16,028) 36,963 36,963 Allocated income taxes ........ (6,632) (12,599) (12,599) (8,285) (11,851) (12,641) (20,345) (20,345) Investment tax credit - deferred (519) (782) (782) (11,331) (6,894) (7,278) (7,278) (7,278) Income tax effect of disallowed costs -- (70,638) (70,638) -- -- -- -- -- Income tax effect of FAS 71 write-off ... -- -- -- -- -- -- (117,998) (117,998) Interest on long-term debt....... 160,795 154,110 154,110 135,115 125,581 118,438 116,137 116,137 Amortization of debt expense and premium-net, and other interest charges 12,195 17,007 17,007 15,826 29,558 24,031 27,984 27,984 One-third of all rentals (Estimated to be representative of the interest component) 5,117 5,992 5,992 5,847 5,221 4,346 4,229 4,229 Interest on in-core fuel 8,278 6,174 6,174 7,185 6,716 4,757 3,842 3,842 Disallowed Clinton plant costs... -- -- 270,956 -- -- -- -- -- FAS 71 Regulatory Write-Offs..... -- -- -- -- -- -- -- 313,030 --------- --------- --------- --------- --------- -------- --------- -------- Earnings (loss) available for fixed $ 359,137 $ 124,707 $ 395,663 $ 425,674 $ 432,647 $ 470,519 $ 23,956 $ 336,986 charges ========= ========= ========= ======== ======== ========= ========= ========= Fixed charges: Interest on long-term debt $ 160,795 $ 154,110 $ 154,110 $ 135,115 $ 125,581 $ 118,438 $ 116,137 $ 116,137 Amortization of debt expense and premium-net, and other interest charges 25,785 27,619 27,619 25,381 38,147 30,663 32,928 32,928 One-third of all rentals (Estimated to be representative of the interest component) 5,117 5,992 5,992 5,847 5,221 4,346 4,229 4,229 --------- -------- -------- --------- --------- --------- --------- --------- Total Fixed Charges........................ $ 191,697 $ 187,721 $ 187,721 $ 166,343 $ 168,949 $ 153,447 $ 153,294 $ 153,294 ========= ========= ========= ========= ========= ========= ========= ========= Ratio of earnings to fixed charges 1.87 0.66* 2.11 2.56 2.56 3.07 0.16* 2.20 ========= ========= ======== ========= ========= ========= ========= ========= * Earnings are inadequate to cover fixed charges. Additional earnings (thousands) for 1993 and 1997 of $63,014 and $129,338, respectively, are required to attain a one-to-one ratio of Earnings to Fixed Charges. ** Supplemental ratio of earnings to fixed charges presented to exclude nonrecurring item - Disallowed Clinton plant costs. *** Supplemental ratio of earnings to fixed charges presented to exclude write-off related to the discontinued application of SFAS 71, "Accounting for the Effects of Certain Types of Regulation" for the generation segment of the business.