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 First Quarter Ended March 31, Years Ended December 31, ----------------- ----------------------------------------------- (millions except ratios) 1996 1995 1995 1994 1993 1992 (1) 1991 ------ ------ ------ ------ ------ ------- ------ Income from continuing operations before provision for income taxes $145.6 $136.7 $458.0 $397.0 $331.6 $179.1 $242.4 Add back fixed charges: Interest on indebtedness 13.8 13.0 55.5 46.4 42.3 41.9 40.7 Interest on ESOP 1.2 1.4 5.3 5.9 6.5 6.9 7.2 Portion of rents representative of interest factor 6.7 7.2 21.4 28.7 26.1 19.2 15.4 ------ ------ ------ ------ ------ ------ ------ Income as adjusted $167.3 $158.3 $540.2 $478.0 $406.5 $247.1 $305.7 ====== ====== ====== ====== ====== ====== ====== Fixed charges and preferred stock dividends: Interest on indebtedness: $ 13.8 $ 13.0 $ 55.5 $ 46.4 $ 42.3 $ 41.9 $ 40.7 Preferred stock dividends 7.8 10.3 37.5 48.4 47.5 20.3 3.5 ------ ------ ------ ------ ------ ------ ------ Interest and dividends 21.6 23.3 93.0 94.8 89.8 62.2 44.2 Interest on ESOP 1.2 1.4 5.3 5.9 6.5 6.9 7.2 Portion of rents representative of interest factor 6.7 7.2 21.4 28.7 26.1 19.2 15.4 ------ ------ ------ ------ ------ ------- ------ Total fixed charges and preferred stock dividends $ 29.5 $ 31.9 $119.7 $129.4 $122.4 $ 88.3 $ 66.8 ====== ====== ====== ====== ====== ====== ====== Ratio of earnings to combined fixed charges and preferred stock dividends 5.7 5.0 4.5 3.7 3.3 2.8 4.6 ====== ====== ====== ====== ====== ====== ====== Ratio of earnings to combined fixed charges and preferred stock dividends (2) 6.8 6.0 5.8 4.8 4.5 4.1 5.9 ====== ====== ====== ====== ====== ====== ====== (1) Income from continuing operations before provision for income taxes excludes the cumulative effect of changes in accounting principles. (2) The calculation of this ratio of earnings to fixed charges reflects the addition of the income from discontinued operations before the provision for income tax component for each period presented. 21