What the IRS actually requires in a mileage log

Most people lose this deduction twice. First by not recording trips, and then by trying to reconstruct them in April from calendar entries and memory — which is exactly the kind of record that does not survive scrutiny.

The requirements themselves are short. It is worth reading them once properly.

#The four things every trip needs

For each business trip you must be able to show:

1. The date of the trip.
2. The destination — where you went.
3. The business purpose — why. "Client meeting — Acme" is enough; "work" is not.
4. The miles driven.

On top of the per-trip record you need your total mileage for the year, because the deduction rests on the share of your driving that was for business. Without a total, a business figure means nothing on its own.

The requirement people miss is purpose. Distance and date come from a phone easily. Purpose has to come from you, and it is the field an examiner reads first.

#Write it down at the time

Records are expected to be kept contemporaneously — at or near the time of the trip. Publication 463 accepts a log maintained weekly that accounts for the week's use as timely. A log assembled months later from memory is weaker evidence, and a log that is suspiciously round (every trip 20 miles, every week identical) invites exactly the questions you do not want.

This is the real argument for automatic tracking. Not that it saves typing, but that the record exists on the day the trip happened rather than the day you needed it.

#Standard rate or actual expenses

Method	What you track	Best when
Standard mileage	Business miles × the published rate — 72.5¢ before 1 July 2026, 76¢ after	Your car is inexpensive to run, or you want the simplest defensible record
Actual expenses	Fuel, insurance, repairs, depreciation — multiplied by your business use percentage	The vehicle is expensive, heavily used for business, or recently bought

You still need the mileage log either way. The actual-expense method needs the business use percentage, and that comes from the same numbers. The rate, the midyear change and a calculator are on the 2026 mileage rate page.

Knowing what a log must contain is one half of it. Knowing how it is judged when somebody reads it is the other: what an auditor rejects in a mileage log lists the six failures, quotes the rule behind each, and ends with a checklist you can score your own log against.

#How long to keep it

Three years from the date you filed is the normal period the IRS has to assess additional tax, so three years is the working answer. Six if a return understated income by more than 25%. There is no time limit where no return was filed.

Storage matters more than people expect. A log that only exists inside an app you have stopped paying for is not a record you control. Keep an export.

#If your app stops logging halfway through the month

This is worth naming, because it is the most common way an otherwise careful record ends up with a hole in it. Several popular trackers cap their free tier by number of drives. MileIQ allows 40 a month, Everlance 30 automatic trips, Driversnote reporting of up to 15, all checked on 21 September 2026. Pass the cap and the app simply stops recording until the month turns over.

The miles you drove after the cap are still deductible. They just are not written down anywhere, and writing them in afterwards is the statement prepared later that this page has been warning about. What a free tier cap does to a tax record works through the arithmetic and compares what each free plan actually allows.

#A note on other countries

The four elements are close to universal, but the arithmetic is not. In the UK, HMRC's approved rate is 55p a mile for the first 10,000 business miles from 6 April 2026 (45p before that) and 25p after — see the 2026/27 HMRC rates. In Canada, the per-kilometre rates apply to employee reimbursement; self-employed filers must use actual expenses and business use percentage, which requires odometer readings at the start and end of the year.

If an app quotes you a single flat rate per mile regardless of country, it is doing the US calculation wherever you live.