IRS Mileage Log Requirements: What Your Log Must Include
By Eyal Malka, Founder of Milebook
November 9, 2026 · 6 min read · Fact-checked against 3 primary sources
If you deduct car expenses, whether at the standard mileage rate or as actual expenses, the IRS expects records that back up how much of your driving was for business. A round number on your tax return with nothing behind it is exactly what gets a deduction denied in an audit.
What a mileage log must show
The regulations (Treas. Reg. §1.274-5T) and IRS Publication 463 ask for these elements for a car used for business:
| Record | What it means in practice |
|---|---|
| Date of each business use | The day of each trip |
| Miles for each business use | Odometer start and end, or the trip distance |
| Business destination | Where you went: client name and address, job site, supplier |
| Business purpose | Why: “site visit”, “delivery”, “client meeting” |
| Total miles for the year | Odometer readings at the start and end of the year, so business use can be shown as a share of all driving |
| When you started using the car for business | The date, recorded once |
| Expenses (for the actual-expense method) | The amount and date of each car expense, with receipts |
How often do you have to update it?
The rules don't require you to write down every trip the moment it ends. They do give much more weight to a record made at or near the time of the trip than to one rebuilt from memory months later. Publication 463 gives a weekly log as an example of a record kept at or near the time.
In practice: log trips daily if you can and weekly at worst. A log reconstructed in April from calendar entries is far weaker, and much more work.
Can you log only part of the year?
Sometimes. The regulations allow an adequate record for a representative part of the year, if you can show that period is typical of the whole year. That suits a steady routine, like the same client route every week. It's risky if your driving varies a lot by season. When in doubt, log everything.
Does an app count?
Yes. The regulations specifically accept records kept on a computer or electronic device with a logging program, as long as they contain the same elements. A phone app that records the date, distance, destination and purpose of each trip meets the same standard as a paper logbook, and is usually more complete.
Keep the receipts too
If you use the actual-expense method, you also need receipts for fuel, repairs, insurance and the rest. Even with the standard rate, keep receipts for business parking and tolls, which you can deduct on top of it. Not sure which method to use? Read our comparison.
Common mistakes
- Counting your commute. Driving between home and your regular workplace is personal, not business.
- Round numbers every week (“100 miles”) with no destinations. Auditors notice.
- No start-of-year odometer reading, so total miles can't be shown.
- A purpose field that just says “business”.
- Mixing two cars in one log without saying which car each trip used.
How Milebook keeps the log for you
In Milebook you log a trip in a few taps: date, start and end odometer (or distance), destination and purpose, marked as business or personal. Odometer readings from your fill-ups fill in the yearly total. Reports add up business miles for any date range, and you can export the full log to a spreadsheet for your tax preparer. See Milebook as a mileage tracker for taxes.
This article is general information, not tax advice. Rules depend on your situation; check with a tax professional.
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About the author
Eyal Malka, Founder of Milebook
Eyal Malka is the founder of Milebook. For more than a decade he has run a home-service business in New York City, with work vans and trucks on the road every day. He tracks fuel, repairs and business mileage for those vehicles himself and claims the mileage deduction every year. Milebook started as the tool he wanted for his own vehicles: one place to see what each one really costs, and a mileage log that's ready at tax time.