Exhibit 10.4.3

FIRST AMENDMENT TO THE CORPORATE OFFICE PROPERTIES TRUST
AMENDED AND RESTATED 2008 OMNIBUS EQUITY AND INCENTIVE PLAN

This First Amendment (this “Amendment”) to the Corporate Office Properties Trust
Amended and Restated 2008 Omnibus Equity and Incentive Plan (the “Plan”), is
made as of March 3, 2011, by Corporate Office Properties Trust, a Maryland real
estate investment trust (the “Company”). All capitalized terms used but not
defined in this Amendment shall have the meanings ascribed to such terms in the
Plan.

1.
The definition of “Minimum Vesting Period” contained in Section 1 of the Plan is
amended by adding the following to the end of such definition:

“as part of retainer, including annual or other grants made pursuant to a
standard compensation policy or arrangement for a Non-Employee Trustee.”

As amended, such definition will read as follows:

“ ‘Minimum Vesting Period’ means, for an Award, the time period beginning on the
date of grant of such Award and ending on (i) in the case of Awards with
conditions or restrictions relating to the attainment of performance goals, the
date that is one (1) year after the date of grant of such Award, or (ii) in the
case of all other Awards, the date that is three (3) years after the date of
grant of such Award; provided, however, that the Minimum Vesting Period shall
not apply to Awards made to Non-Employee Trustees as part of a retainer,
including annual or other grants made pursuant to a standard compensation policy
or arrangement for a Non-Employee Trustee.”

2.
All other terms and conditions of the Plan shall be unchanged and remain in full
force and effect.

    
ADOPTED:
March 3, 2011
 
Corporate Office Properties Trust
 
 
 
 
 
 
 
By: /s/ Randall M. Griffin, Chief Executive Officer
 
 
 
Randall M. Griffin, Chief Executive Officer