What the IRS Actually Wants in a Mileage Log

The mileage deduction is one of the biggest write-offs the self-employed get, and also one of the easiest for the IRS to throw out. The deduction itself is generous. For 2026 it is 72.5 cents for every business mile. But the rate only helps if your record of those miles would survive a second look. A weak log is the difference between a deduction you keep and one you lose. Here is what the IRS actually wants to see.

What every trip entry needs

The IRS lays this out in Publication 463, and it is not complicated. For each business trip, your record should show four things:

• The date of the trip
• The miles you drove
• Where you went
• The business reason for the drive

That last one is the piece people skip, and it is the piece that matters most. A row that says "42 miles" with no purpose looks like it could have been a personal errand. "42 miles, drove to the Henderson site to meet the inspector" is a deduction nobody can argue with.

Why the timing matters

The rules ask for a contemporaneous record, which is a formal way of saying you kept it as you went, not after the fact. A log you sit down and invent in April from credit card receipts and memory is exactly the kind of thing that gets disallowed in an audit. The IRS knows the difference between a record kept all year and one reconstructed the night before filing. You do not have to write a novel for each trip. A quick note logged at the time is worth far more than a polished spreadsheet built from guesses.

Your commute does not count

This catches people every year. Driving from home to your regular place of work is a personal commute, and it is never deductible, no matter how far it is. What does count is business driving: trips between job sites, drives to see clients, runs to the supply house or the bank for the business. If you work out of a qualifying home office, the math can shift, because trips from a home office to business stops can be business miles rather than commuting.

Total miles, not just business miles

One thing people forget is that you also need your total miles for the year, not only the business ones. The deduction works off the business share of your driving, so the IRS wants to see the whole picture. The simple habit is to jot your odometer reading at the start and end of the year, then log every business trip in between as it happens.

The most defensible log is automatic

The strongest record you can keep is one you do not have to remember to keep. A GPS app that logs each drive with the date, the distance, and the route, and lets you tag the business purpose, captures exactly the detail the rules ask for, without you scribbling in a notebook at every stop. If the standard rate is new to you, our guide to the 2026 IRS mileage rate covers how the deduction itself works.

How Vuuv helps

Vuuv's mileage tracking records your trips as you drive, saving the date, the miles, the route, and the business reason in one place. There is nothing to reconstruct in April, because the contemporaneous log the IRS wants already exists. You just confirm which trips were business and the deduction is ready.

This article is general information, not tax advice. Tax rules change and every situation is different. Confirm the details against current IRS guidance or talk to a qualified tax professional before you file.