Per Diem and Mileage: What Each One Pays For

A per diem is a fixed daily amount for lodging and meals and incidental expenses while an employee travels away from home on business. It is quoted for a place and a date, which is why it is paid per day rather than per mile.

The allowance covers the room and the food. It does not cover the cost of getting to the destination, and it does not pay for local driving. Those are transport costs, and a mileage rate is how an employer usually pays for them.

A per diem is not a receipt waiver. An accountable plan can accept the daily figure as proof of the amount, but the employer still needs the dates, the place and the business purpose of the trip.

A mileage rate is a price per mile for using a personal vehicle on business. The standard rate is built to cover the running and ownership costs of the car, so fuel, servicing, insurance and wear are already inside the figure rather than claimed beside it.

The rate applies to business miles, not to days. A trip of 300 miles pays for 300 miles whatever the calendar says, and a day with no business driving pays nothing under the mileage rate.

Parking and tolls are normally paid as separate costs rather than as part of the rate. They are not a per diem, and they do not turn one mileage claim into two.

Three federal sources set the figures a US trip can use. GSA sets the per diem for the 48 contiguous states and the District of Columbia. The Defense Travel Management Office sets the per diem for Alaska, Hawaii and the US territories. The Department of State sets the per diem for foreign travel.

The mileage figure is separate. GSA sets the privately owned vehicle rate from the IRS standard mileage rate, and the IRS rate is also the figure a tax deduction uses.

A state can set its own travel allowance for state employees, and some do. A private employer can adopt a federal figure, use a state figure or set its own, so the written policy decides what a claim follows.

The per diem table applies to travel from October 1, 2026 through September 30, 2027. The US mileage rate applies to a trip on the date it is driven, and it changed on July 1, 2026.

Last checked October 31, 2026 against the GSA bulletin for the fiscal year, the GSA vehicle rate bulletin and IRS Publication 463.

The per diem vs mileage question covers whether a per diem replaces mileage, how an accountable plan handles both payments and what a self-employed return does with the same two figures.

The GSA question covers why a midyear IRS change moves the vehicle rate and leaves the per diem table alone.

The rate finder lists every published figure by country and year, and the current US rate is listed by the IRS. The calculator prices a trip at the rate for its date, and the state guide covers the rules an employer follows.