It typically details the principal balance, interest due as of that date, per diem, any late fees, etc. By including a per diem amount in the letter, the parties will not have to execute another payoff letter if the termination date.The first step is to get in touch with your lender or loan servicer. You can find their contact information on your monthly statements. Calculate your per diem allowance for your trip. Simply enter your travel dates and details to find out your per diem allowance. Disclaimer: This form is provided as a service of the Michigan Association of REALTORS®. Per diem rates lookup Allowances for lodging, meal and incidental costs while on official government travel. Michigan per diem calculator. Input the dates of your business travel, along with the location, county, and city, to calculate your per diem allowance.