Comerica (CMA) 8-K Other Events

Exhibit 12.1

Computation of Ratios of Earnings to Fixed Charges

	For the six months ended June 30,		For the years ended December 31,
(dollars in millions)	2010		2009			2008		2007		2006		2005
Earnings:
Income (loss) before income taxes	$	123	$	(115	)	$	271	$	988	$	1,165	$	1,220
Plus:
Fixed charges		128		565			1,260		1,748		1,457		788
Earnings, including interest on deposits		251		450			1,531		2,736		2,622		2,008
Less:
Interest on deposits		64		372			734		1,167		1,004		548
Earnings, excluding interest on deposits	$	187	$	78		$	797	$	1,569	$	1,618	$	1,460
Fixed charges:
Interest expense	$	115	$	538		$	1,236	$	1,727	$	1,439	$	770
Interest portion of rental expense		13		27			24		21		19		18
Total fixed charges		128		565			1,260		1,748		1,458		788
Less:
Interest on deposits		64		372			734		1,167		1,004		548
Total fixed charges, excluding interest on deposits	$	64	$	193		$	526	$	581	$	454	$	240
Earnings to fixed charges:
Including interest on deposits		1.95x		(a	)		1.21x		1.57x		1.80x		2.55x
Excluding interest on deposits		2.92x		(a	)		1.51x		2.70x		3.57x		6.10x

(a) For the year ended December 31, 2009, earnings were insufficient to cover combined fixed charges, excluding or including interest on deposits, by $115,000,000.