Per diem is an allowance for lodging, meals, and incidental expenses. The US General Services Administration (GSA) establishes the per diem reimbursement rates.It typically details the principal balance, interest due as of that date, per diem, any late fees, etc. The first step is to get in touch with your lender or loan servicer. You can find their contact information on your monthly statements. Per diem rates lookup Allowances for lodging, meal and incidental costs while on official government travel. Of interest per day. I. Submittal Overview. An employee is not required to attach meal receipts to the voucher, when traveling for more than 24 hours. Per Diem rates are used.