COPT Defense Properties (CDP) 8-K Other Events

EXHIBIT 12.1

Corporate Office Properties, L.P. and Subsidiaries

Ratio of Earnings to Fixed Charges

(Dollars in thousands)

	Three Months Ended			Years Ended December 31,
	March 31, 2013			2012			2011			2010			2009			2008
Earnings:
Income (loss) from continuing operations before equity in (loss) income of unconsolidated entities and income taxes	9,112			$	7,570		$	(88,277	)	$	24,377		$	46,150		$	44,951
Gain on sales of real estate, excluding discontinued operations	2,354			21			2,732			2,840			—			1,682
Fixed charges (from below)	25,020			111,825			122,397			119,074			98,252			105,633
Amortization of capitalized interest	513			1,798			1,610			1,363			1,105			890
Distributed loss of equity investees	—			—			(31		)	—			—			(203		)
Subtract:
Capitalized interest (from below)	(2,440		)	(13,903		)	(17,400		)	(16,524		)	(15,461		)	(18,312		)
Total earnings	$	34,559		$	107,311		$	21,031		$	131,130		$	130,046		$	134,641
Fixed charges:
Interest expense on continuing operations	$	22,307		$	94,624		$	98,222		$	95,729		$	76,718		$	79,542
Interest expense on discontinued operations	64			2,174			6,079			6,399			5,702			7,379
Capitalized interest (internal and external)	2,440			13,903			17,400			16,524			15,461			18,312
Amortization of debt issuance costs-capitalized	101			649			183			19			30			32
Interest included in rental expense	108			475			513			403			341			368
Total fixed charges	$	25,020		$	111,825		$	122,397		$	119,074		$	98,252		$	105,633
Ratio of earnings to fixed charges	1.38			0.96			0.17			1.10			1.32			1.27
Deficiency				$	4,514		$	101,366