Per diem (a daily rate allowable for meals and incidentals) may only be used for international travel. The U.S. Department of State lists the maximum daily allowable foreign per diem rates for cities in countries throughout the world. You can view the rates here. We ask that, once your trip is completed, you review your meal receipts and claim a daily rate that fairly reimburses you rather than the full allowable amount listed on the U.S. Department of State website.
Per diems are not permitted for domestic travel, actual costs must be used.