The four things every business drive needs
If you claim business miles, the IRS can ask you to prove them. For each business drive, your log should show:
- The date. It also decides which rate applies; in 2026 the rate changed on July 1.
- Where you went. The destination, such as a client's address or a job site.
- Why you went. The business reason: “Site visit, Lopez kitchen remodel”, not just “work”.
- How far. The miles for that drive.
You also need the total miles you drove that year, business and personal, so your business share can be checked. The easy way is to note the odometer on January 1 and December 31.
What a good log looks like
| Date | From → To | Purpose | Miles |
|---|---|---|---|
| Oct 13 | Home → 95 Trade St, Aurora | Quote for porch repair | 18.3 |
| Oct 13 | 95 Trade St → Home Depot, Naperville | Materials for porch job | 6.1 |
| Oct 14 | Home → Fox River Commons | Personal | 2.1 |
Write it down at the time
The IRS gives more weight to a log kept as you go than one put together later from memory. You don't have to write each drive down the moment you park, though: a log you fill in once a week counts as kept on time.
A log rebuilt at tax time from a calendar and guesswork is the weakest kind. Missing drives are also the most common way people lose deductions they were owed.
Paper, spreadsheet or app
Any of them works. The IRS accepts a notebook, diary, trip sheets or a similar record, and says records kept on a computer count too. What matters is that it's complete and made close to the time.
Keep receipts for business parking and tolls, since those are deductible on top of the mileage rate.
How long to keep it
Keep your log for at least three years from the date you file the return that uses it. Records for a car you depreciate need keeping longer, so many people simply keep every year's log.
What MileLock records for you
MileLock notices when you start driving and records the date, the start and end times, where you started and finished, and the miles, without you opening the app. You swipe each drive business or personal, and export the year as a PDF or spreadsheet for your tax preparer.
The one thing it can't know is why you went. Your calendar or invoices usually show it; keep them with the log.
Sources
This guide explains the IRS rules in plain English. It isn't tax advice; for your own situation, ask a tax professional.
Let MileLock keep the log for you
It records every drive on its own, you swipe business or personal, and the IRS-ready log is one tap away. Free for 30 drives a month.
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