IRS Mileage Reimbursement Rules for Employers

Every employer that puts staff on the road eventually has to decide how to pay them back for it — and the choice between mileage reimbursement and a flat car allowance has real payroll-tax consequences that aren't always obvious until an audit flags them.

The baseline rule

Employers can reimburse employees for business mileage tax-free — but only when the reimbursement follows IRS accountable plan rules and stays within the standard mileage rate for the date of travel. Here's exactly what that requires in practice.

The 2026 IRS standard mileage rate

The IRS sets the optional standard mileage rate each December for the following year, and for 2026 it opened at 72.5 cents per mile for business use. On July 1, 2026, the IRS made a rare mid-year adjustment, raising the rate to 76 cents per mile in response to rising fuel costs — see our full breakdown of the 2026 mileage rate. Reimbursing at or below the applicable rate for the date of travel keeps the payment outside the employee's gross income entirely.

What makes a mileage reimbursement tax-free

• The reimbursement is for actual business driving — not commuting or personal trips.
• The employee submits a mileage log with dates, destinations, business purpose and miles within a reasonable time, generally within 60 days.
• The reimbursement amount does not exceed the IRS rate in effect on the date of travel (72.5¢ before July 1, 76¢ from July 1).

When reimbursement becomes taxable

• You pay above the applicable rate for the date of travel (72.5 cents before July 1, 76 cents from July 1) — the excess is wages.
• Employees don't submit logs — the entire reimbursement is a taxable non-accountable plan payment, as covered in our accountable plan guide.
• You pay a flat car allowance with no log requirement — the full allowance is taxable, regardless of how much of it genuinely went toward business driving.

“Mileage allowances paid at a rate that does not exceed the standard mileage rate are deemed substantiated if the employee substantiates the time, place, and business purpose of the travel.”

— Internal Revenue Service, per diem and mileage substantiation guidance, irs.gov

FAVR: an alternative to the IRS rate

Fixed and Variable Rate (FAVR) reimbursement programmes calculate a per-mile rate based on actual regional fuel and insurance costs rather than the single national IRS figure. They can legally exceed the IRS standard mileage rate without triggering income tax, but they require IRS-approved actuarial data and considerably more administration — see our full FAVR explainer for who this actually suits.

Car allowances vs. mileage reimbursement

A monthly car allowance (for example, $500/month) paid without mileage logs is taxable income to the employee in full, regardless of how much business driving actually happened. Mileage reimbursement — paying per mile driven for business, properly documented — is tax-free when done correctly. Most employers find the mileage approach creates significantly less payroll-tax exposure across their whole travelling workforce.