Reimbursement for meals is based on the actual meal expense, not estimates. As an alternative, travelers may choose to use the Per Diem reimbursement method when overnight travel is involved. The per diem method allows for a flat sum amount per day to cover daily meals and incidental expenses in lieu of actual costs. Per diems eliminate the need to track actual cost and receipts for covered expenses. Only one reimbursement method is allowed per trip.
Guidelines for actual expense reimbursement
Payment of a flat sum amount to cover meals and incidentals