<Page> <Table> <Caption> EXHIBIT 12(B) AON CORPORATION AND CONSOLIDATED SUBSIDIARIES COMBINED WITH UNCONSOLIDATED SUBSIDIARIES Computation of Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends YEARS ENDED DECEMBER 31, - ----------------------------------------------------------------------------------------------------------------------------- (millions except ratios) 2001 2000 1999 1998 1997 ------ ------ ------ ------ ------ (Restated) (Restated) (Restated) (Restated) (Restated) Income before provision for income taxes and minority interest $ 309 $ 854 $ 635 $ 931 $ 542 ADD BACK FIXED CHARGES: Interest on indebtedness 127 140 105 87 70 Interest credited on investment-type insurance contracts 56 71 77 72 45 Interest on ESOP - - 1 2 3 Portion of rents representative of interest factor 57 54 49 51 44 ------ ------- ------ ------- ------- INCOME AS ADJUSTED $ 549 $ 1,119 $ 867 $ 1,143 $ 704 ====== ======= ====== ======= ======= FIXED CHARGES AND PREFERRED STOCK DIVIDENDS: Interest on indebtedness $ 127 $ 140 $ 105 $ 87 $ 70 Preferred stock dividends 70 70 70 70 82 ------ ------- ------ ------- ------- INTEREST AND DIVIDENDS 197 210 175 157 152 Interest credited on investment-type insurance contracts 56 71 77 72 45 Interest on ESOP - - 1 2 3 Portion of rents representative of interest factor 57 54 49 51 44 ------ ------- ------ ------- ------- TOTAL FIXED CHARGES AND PREFERRED STOCK DIVIDENDS $ 310 $ 335 $ 302 $ 282 $ 244 ====== ======= ====== ======= ======= RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS (1) 1.8 3.3 2.9 4.1 2.9 ====== ======= ====== ======= ======= </Table> (1) Included in total fixed charges and preferred stock dividends are $66 million for the years ended December 31, 2001, 2000, 1999 and 1998 and $64 million for the year ended December 31, 1997, of pretax distributions on the 8.205% mandatorily redeemable preferred capital securities which are classified as "minority interest" on the consolidated statements of income.