IRS mileage log requirements: what to record for every trip
Car expenses are one of the deductions the IRS holds to a stricter standard of proof. Estimates reconstructed at tax time are routinely thrown out in audits. A simple log, kept as you go, is what makes the deduction stick.
Key takeaways
- Record the date, destination, business purpose, and miles for each business trip.
- Keep the log at or near the time of the trip. A record made months later is far weaker.
- Track your total miles for the year, too, so business use can be calculated.
- Commuting from home to a regular workplace is not deductible, no matter how far.
What the log needs to show
Section 274(d) of the tax code requires “adequate records” for vehicle expenses. Publication 463 spells out what that means for each business use of the car:
| Element | What to write down | Example |
|---|---|---|
| Date | The day of the trip | Mar 4, 2026 |
| Place | Where you went: address, client, or site | Client office, 410 Main St |
| Business purpose | Why the trip was for business | Kitchen remodel walkthrough |
| Miles | Business miles for the trip, or start and end odometer | 18.4 mi |
Add the vehicle’s odometer reading at the start and end of the year. Total miles tell the IRS what share of the car’s use was business, which matters most under the actual expense method.
Why “at or near the time” matters
The regulations give a record made at or near the time of the expense high credibility. A log rebuilt from memory at the end of the year has to be backed up by other evidence, and courts have repeatedly disallowed deductions based on after-the-fact estimates.
You don’t have to write in a notebook while you drive. A phone app that records the trip, or a calendar entry made the same day with the destination and purpose, counts as a timely record.
Which drives count as business
- Not deductible: driving between your home and your regular place of work, even if you take calls on the way.
- Deductible: driving from your regular workplace to a client, job site, supplier, or bank for business.
- Deductible: driving from home to a temporary work location, such as a job site you work at for a limited time.
- Deductible: if your home office is your principal place of business, trips from home to other work locations are generally business trips, not commutes. See the home office guide.
Common mileage log mistakes
- Round numbers on every trip (20, 40, 60 miles), which look estimated.
- No business purpose, or a generic one like “business” for every trip.
- Claiming close to 100% business use for the only car in the household.
- Mixing personal stops into a business trip without separating the miles.
- Applying one rate to all of 2026, when the rate changed on July 1. See the 2026 rate guide.
Frequently asked questions
Does the IRS require a specific mileage log format?
No. Any format works (paper, spreadsheet, or app) as long as it shows the date, place, business purpose, and miles for each trip and was kept at or near the time.
Can I use Google Maps history as a mileage log?
Location history can help support a log, but on its own it usually lacks the business purpose for each trip. Add the purpose at the time and you have a much stronger record.
How long should I keep my mileage log?
Keep it with your tax records for at least three years after you file, and longer in the situations described in our record retention guide.
Sources
- IRS Publication 463, Travel, Gift, and Car Expenses
- Treasury Regulation §1.274-5T, substantiation requirements
This guide is general information for U.S. federal taxes, current as of October 21, 2026. It isn’t tax, legal, or accounting advice. Talk to a qualified professional about your situation.
Keep the records
this guide asks for.
spentr captures receipts, business miles, and rental hours as they happen, so they’re ready when you file.