UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

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Corporate Office Properties Trust
(Name of Registrant as Specified In Its Charter)


(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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M55881-P37278 You are receiving this communication because you hold shares in the company named above. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. CORPORATE OFFICE PROPERTIES TRUST *** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on May 9, 2013. CORPORATE OFFICE PROPERTIES TRUST 6711 COLUMBIA GATEWAY DRIVE, SUITE 300 COLUMBIA, MD 21046 Meeting Information Meeting Type: Annual Meeting For holders as of: March 15, 2013 Date: May 9, 2013 Time: 9:30 AM EDT Location: Corporate Office Properties Trust 6711 Columbia Gateway Drive Suite 300 Columbia, MD 21046 See the reverse side of this notice to obtain proxy materials and voting instructions.

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: How To Vote Please Choose One of the Following Voting Methods Vote In Person: Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares. Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow (located on the following page) available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before April 25, 2013 to facilitate timely delivery. How to View Online: Have the information that is printed in the box marked by the arrow (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL*: sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line. NOTICE AND PROXY STATEMENT ANNUAL REPORT . XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX M55882-P37278 Proxy Materials Available to VIEW or RECEIVE:

Voting Items M55883-P37278 1. Election of Trustees Nominees: The Board of Trustees recommends that you vote "FOR" the listed nominees: 1j) Kenneth D. Wethe 1i) Roger A. Waesche, Jr. 1h) Richard Szafranski 1g) Steven D. Kesler 1d) Robert L. Denton 1f) David M. Jacobstein 1c) Thomas F. Brady 1e) Elizabeth A. Hight 1b) Clay W. Hamlin, III 1a) Jay H. Shidler 3. Approval, on an Advisory Basis, of Named Executive Officer compensation. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. 2. Ratification of the Appointment of Independent Registered Public Accounting Firm. The Board of Trustees recommends you vote "FOR" Proposals 2 and 3.