How to Calculate Mileage Reimbursement (2026 Rules)

Mileage reimbursement looks like the simplest math in expense reporting — miles times rate — and in 2026 it tripped up half the internet anyway, because the IRS changed the business rate in the middle of the year. Here is the calculation done properly.

The formula

Reimbursement = miles driven × the IRS rate in effect on the driving date. That last clause matters this year. Drive 350 business miles in May 2026 and the rate is 72.5¢: $253.75. Drive the same 350 miles in August and it is 76¢: $266.00. The filing date, approval date, and payment date are all irrelevant — only the driving date decides.

Why 2026 has two rates

The IRS set the 2026 business rate at 72.5¢ per mile in December 2025 (Notice 2026-10), then raised it to 76¢ effective July 1, 2026 — only the second mid-year adjustment since 2022. Mid-year changes happen when vehicle operating costs move sharply; the 2022 precedent (58.5¢ → 62.5¢ that July) followed the fuel-price spike. Practical consequence: any table or calculator showing a single "2026 rate" is wrong for half the year, and expense reports spanning June–July need the trip split by date.

The four purpose categories

• Business — 72.5¢ then 76¢ in 2026. Work travel in a personal vehicle: client visits, between-office driving, work errands. Ordinary commuting from home to your regular workplace does not qualify.
• Medical — 21¢. Driving to receive medical care.
• Moving — 21¢, active-duty military moves under permanent-change-of-station orders only.
• Charity — 14¢, fixed by statute rather than set annually, which is why it has not moved in decades.

Round trips, rounding, and precision

Count actual miles driven, both directions. Compute once, round once: 17 miles each way is 34 miles × 76¢ = $25.84 — not two 17-mile legs rounded separately. At 72.5¢ the half-cent matters: 3 miles is 217.5¢, which rounds to $2.18. Trivial on one trip, real money across a year of claims.

What the rate does and does not cover

The standard rate is an all-in per-mile figure: fuel, maintenance, tires, depreciation, insurance. Tolls and parking are not inside it — they are claimable separately under most policies. And the IRS rate itself is a standard, not a law binding employers: companies may reimburse above it, below it, or per their own scheme. Check your policy; the IRS figure is the reference point nearly everyone starts from.

Keep a log that survives scrutiny

For each trip: date, purpose, start and end points, and miles. The date column is what makes a split-rate year like 2026 painless — your May trips and August trips land in the right rate bucket automatically. Odometer photos at the start and end of long trips are cheap insurance.

For any specific distance, the computed pages give exact amounts for every purpose and both 2026 periods — for example 350 miles, 100 miles, or the full 2026 rate reference.