COVID-19 tamped down business travel, but travel has picked up considerably. From a tax perspective, the cost of business travel can be deductible provided there is proper substantiation. The tax law is specific on what is needed for this purpose, including a record—written or online—of the business purpose for the expense, the dates of the travel, the destination, and amounts spent on each separate expense for lodging, meals, etc. (Code §274(d)). In addition, documentary evidence, such as receipts, is needed to back up each expense. However, business travelers may use certain government sets certain per diem rates to substantiate the cost of business travel—lodging, meals, and incidental expenses. Relying on these per diem rates avoids the need to retain receipts and other evidence of cost. There are three different per diem rates as explained below.