Mileage Logs: What the IRS Will Accept, and What It Won't
A reconstructed spreadsheet made in April is the weakest possible evidence. Here is what a contemporaneous log needs, and the 2026 rate change most people miss.
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The mileage deduction is generous and easy to calculate. It is also the one most often lost at audit, and almost always for the same reason: the log was created afterwards.
The rate changed mid-year
Start here, because most calculators still get it wrong.
The IRS raised the business standard mileage rate partway through 2026. The official rate table confirms both figures:
| Period | Rate |
|---|---|
| 1 January – 30 June 2026 | 72.5¢ per mile |
| 1 July – 31 December 2026 | 76¢ per mile |
A single blended rate applied to the whole year is wrong in both directions. If your driving was uneven across the year, the error is not small.
The mileage calculator takes the two halves separately.
What a log actually needs
Four things per trip:
- Date
- Destination
- Business purpose — "client meeting, Acme Corp" not "work"
- Miles driven
Plus, once a year: your total mileage, so the business percentage can be established. An odometer photo on 1 January and 31 December is the easiest way.
Contemporaneous is the word that matters
A log kept as you drive is strong evidence. A spreadsheet reconstructed in April from your calendar is weak evidence, and the IRS knows the difference — the round numbers give it away. Reconstruction is better than nothing, but it is the weakest position you can take into a question.
The commuting line
Not deductible: home to a regular place of work, and back. That is commuting, whatever the vehicle and whoever pays for it.
Deductible: travel between client sites during a working day, trips to suppliers, to the bank for business, to the post office with client work.
The useful exception: if your home office is your principal place of business, trips from home to a client site are business miles rather than commuting. For most freelancers with a qualifying home office, that converts a lot of driving from non-deductible to deductible — and it is the main reason the home office deduction is worth more than its face value.
Standard rate or actual expenses
The standard rate covers fuel, maintenance, insurance, depreciation and registration in one number. Simple, and usually larger for ordinary cars.
Actual expenses means tracking every vehicle cost and applying your business-use percentage. It wins for expensive vehicles, heavy depreciation, or unusually low mileage on a costly car.
Decide in year one
If you want the option to use the standard rate later, you generally must use it in the first year the car is in service. Starting with actual expenses can lock you out. Make this choice deliberately rather than discovering it at your second filing.
Parking and tolls for business trips are deductible on top of either method.
The realistic system
An app that logs trips from your phone's motion sensors and lets you swipe each one business or personal. MileIQ, Everlance, and several others do this. A few dollars a month, itself deductible.
If you would rather not, a notebook in the glovebox works — the IRS has never required software. What it requires is that the record was made at the time.
What does not work is intending to remember. Nobody does.