Exhibit 12(a)

Aon Corporation and Consolidated Subsidiaries

Combined With Unconsolidated Subsidiaries

Computation of Ratio of Earnings to Fixed Charges

	Nine Months Ended Sept. 30,				Years Ended December 31,
(millions except ratios)	2004		2003		2003		2002		2001			2000		1999
Income from continuing operations before provision for income taxes and minority interest	$	770	$	773	$	1,131	$	840	$	367		$	846	$	622
Less: Earnings from unconsolidated entities under the equity method of accounting	33		30		49		19		(139		)	44		50
Add back fixed charges:
Interest on indebtedness	101		79		101		124		127			140		105
Interest credited on deposit-type insurance contracts	1		3		—		29		56			71		77
Interest on ESOP	—		—		—		—		—			—		1
Portion of rents representative of interest factor	50		41		67		59		57			54		49
Income as adjusted	$	889	$	866	$	1,250	$	1,033	$	746		$	1,067	$	804
Fixed charges:
Interest on indebtedness (1)	$	101	$	79	$	101	$	124	$	127		$	140	$	105
Interest credited on deposit-type insurance contracts	1		3		—		29		56			71		77
Interest on ESOP	—		—		—		—		—			—		1
Portion of rents representative of interest factor	50		41		67		59		57			54		49
Total fixed charges	$	152	$	123	$	168	$	212	$	240		$	265	$	232
Ratio of earnings to fixed charges	5.8		7.0		7.4		4.9		3.1			4.0		3.5

(1)As a result of the adoption of FIN 46 on December 31, 2003, Aon was required to deconsolidate its 8.205% mandatorily redeemable preferred capital securities. This decrease was offset by an increase in notes payable. Beginning in 2004, interest expense ($43 million for the nine months ended September 30, 2004) on these notes payable is reported as part of interest expense in the condensed consolidated statements of income.