Fill out the order form with all the required fields. After the submission of your request, you may forward documents via email.By including a per diem amount in the letter, the parties will not have to execute another payoff letter if the termination date. GSA establishes the maximum CONUS (Continental United States) Per Diem rates for federal travel customers. Typically your monthly statement only shows your principal balance. This is not a payoff balance. The first step is to get in touch with your lender or loan servicer. You can find their contact information on your monthly statements. The maximum per diem rates are updated annually in the Statewide Financial System to coincide with federal GSA rate changes. Process and Document Preparation:.