Exhibit 12.1
Corporate Office Properties Trust
Ratio of Earnings to Combined Fixed Charges and Preferred Share Dividends
(Dollars in thousands)
	Years Ended December 31,
	2012			2011			2010			2009			2008
Earnings:
Income (loss) from continuing operations before equity in (loss) income of unconsolidated entities and income taxes	$	7,570		$	(88,283	)	$	24,353		$	46,126		$	44,919
Gain on sales of real estate, excluding discontinued operations	21			2,732			2,840			—			1,682
Combined fixed charges and preferred share dividends (from below)	133,345			139,159			135,836			115,014			122,395
Amortization of capitalized interest	1,798			1,610			1,363			1,105			890
Distributed loss of equity investees	—			(31		)	—			—			(203		)
Subtract:
Capitalized interest (from below)	(13,903		)	(17,400		)	(16,524		)	(15,461		)	(18,312		)
Preferred share dividends included in fixed charges	(20,844		)	(16,102		)	(16,102		)	(16,102		)	(16,102		)
Preferred unit distributions included in fixed charges	(676		)	(660		)	(660		)	(660		)	(660		)
Total earnings	$	107,311		$	21,025		$	131,106		$	130,022		$	134,609
Combined Fixed Charges and Preferred Share Dividends:
Combined fixed charges and preferred share dividends:
Interest expense on continuing operations	$	94,624		$	98,222		$	95,729		$	76,718		$	79,542
Interest expense on discontinued operations	2,174			6,079			6,399			5,702			7,379
Capitalized interest (internal and external)	13,903			17,400			16,524			15,461			18,312
Amortization of debt issuance costs-capitalized	649			183			19			30			32
Interest included in rental expense	475			513			403			341			368
Preferred share dividends	20,844			16,102			16,102			16,102			16,102
Preferred unit distributions	676			660			660			660			660
Total combined fixed charges and preferred share dividends	$	133,345		$	139,159		$	135,836		$	115,014		$	122,395
Ratio of earnings to combined fixed charges and preferred share dividends	0.80			0.15			0.97			1.13			1.10
Deficiency	$	26,034		$	118,134		$	4,730