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)
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*** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on May 10, 2018. CORPORATE OFFICE PROPERTIES TRUST 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 CORPORATE OFFICE PROPERTIES TRUST 6711 COLUMBIA GATEWAY DRIVE, SUITE 300 COLUMBIA, MD 21046 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. proxy materials and voting instructions. E38656-P04239 See the reverse side of this notice to obtain Meeting Information Meeting Type:Annual Meeting For holders as of:March 12, 2018 Date: May 10, 2018Time: 9:30 AM EDT Location: Corporate Office Properties Trust 6711 Columbia Gateway Drive First Floor Sustainability Suite Columbia, MD 21046

Before You Vote How to Access the Proxy Materials Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX XXXX (located on the by the arrow XXXX XXXX XXXX XXXX (located on the following page) in the subject line. How To Vote Please Choose One of the Following Voting Methods marked by the arrow XXXX XXXX XXXX XXXX (located on the following page) available and follow the instructions. E38657-P04239 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 Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. Proxy Materials Available to VIEW or RECEIVE: NOTICE AND PROXY STATEMENTANNUAL REPORT How to View Online: 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 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 26, 2018 to facilitate timely delivery.

The Board of Trustees recommends that you vote "FOR" the listed nominees: 1. Election of Trustees Nominees: The Board of Trustees recommends you vote "FOR" Proposals 2, 3 and 4. 1a) Thomas F. Brady 2. Ratification of the Appointment of Independent Registered Public Accounting Firm. 1b) Stephen E. Budorick 3. Approve Amendment to Amended and Restated Declaration of Trust Granting Shareholders the Right to Approve a Merger or Business Combination by Simple Majority Vote. 1c) Robert L. Denton, Sr. 1d) Philip L. Hawkins 4. Approval, on an Advisory Basis, of Named Executive Officer Compensation. 1e) David M. Jacobstein NOTE: Such other business as may properly come before the meeting or any adjournment thereof. 1f) Steven D. Kesler 1g) C. Taylor Pickett 1h) Lisa G. Trimberger E38658-P04239 Voting Items

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