The terms of a contract or any work authorization may be modified with a supplemental agreement/work authorization if the ROW Program Office determines that there has been a significant change in (1) the scope, complexity or character of the service to be performed; or (2) the duration of the work. Additional compensation, if appropriate, shall be paid as specified in Attachment D. The cumulative total of all work authorizations combined shall not exceed the contract's maximum amount total, which will vary based upon the ROW Program Office requirements at the time the contract is awarded. Any supplemental agreement must be executed by both parties within the work authorization and contract periods.

The appraiser may not modify the scope of work or extend the expiration date on a work authorization without the execution of a supplemental agreement and authorization to proceed by the ROW Program Office.

All work authorizations must be issued within two years of the date of final execution of the work authorization, unless modified by a supplemental work authorization. No work authorization may extend beyond the contract period.