By including a per diem amount in the letter, the parties will not have to execute another payoff letter if the termination date. Please review the attached payment scenarios.Link to GSA Per Diem Rates; Download this pdf file. It typically details the principal balance, interest due as of that date, per diem, any late fees, etc. Calculate your per diem allowance for your trip. Simply enter your travel dates and details to find out your per diem allowance. Total per diem will auto fill. 84. Per diem allowance refers to the maximum food allowance for which employees can be reimbursed per day. How to fill out an Employee Expense Statement. This form should be completed on-line and then printed.