What information does an IRS mileage log need?

Five things for every business trip: the date, your starting point, your destination, the business purpose of the trip, and the miles driven. You also need your vehicle's odometer reading at the beginning and end of the tax year, and whenever you start using a new vehicle for business.

What does contemporaneous mean?

It means the record was created at or near the time of the trip rather than reconstructed later. In practice that means logging the same day, or within a few days at most. Logs rebuilt from memory months afterwards are treated with suspicion and are frequently rejected in an audit.

Is a phone app acceptable to the IRS?

Yes. The IRS accepts paper notebooks, spreadsheets, PDFs and apps equally, as long as the required information is present and accurate. GPS based apps tend to produce the strongest records available because they capture the data in real time, which satisfies the contemporaneous requirement by design.

How long do I need to keep mileage records?

Keep them at least three years from the date you filed the return, which is the normal IRS assessment window. Six years is safer if there is any chance of a substantial understatement of income. Digital records are far easier to keep this long than a glovebox notebook.

IRS mileage log requirements

By Isaac Farris·Updated August 7, 2026·7 minute read

Most people who lose a mileage deduction do not lose it because they were not driving. They lose it because the record does not meet the standard, and they find that out at the worst possible moment.

What every trip needs

Date of the trip
Starting location
Destination
Business purpose, in enough words to be meaningful
Miles driven

Plus your odometer reading at the start and end of the tax year, and whenever you begin using a different vehicle for business.

The rule that actually matters

The requirement people underestimate is the contemporaneous one. The IRS expects the record to be made at or near the time of the trip. Not at the weekend, not at the end of the month, and certainly not in April from a calendar and a fuel receipt.

This is not a technicality. It is the first thing examined in an audit, and a log that looks reconstructed undermines every entry in it, including the trips that genuinely happened. Auditors see a great many rebuilt logs and they recognise the pattern immediately: round numbers, suspiciously regular entries, and purposes written in identical phrasing.

What a good purpose entry looks like

"Business" is not a purpose. Neither is "client". The entry needs to identify the trip well enough that someone reading it two years later can see why it was work.

Weak: Client visit
Better: On site quote, Henderson kitchen remodel, 14 Elm St
Weak: Supplies
Better: Collected tile order from Watsonville Supply for Henderson job

Formats the IRS accepts

All of these are acceptable, and none is inherently better in the eyes of the IRS:

A paper notebook in the vehicle
A spreadsheet
An exported PDF
A mileage tracking app

What differs is how likely each is to be complete. A notebook works perfectly if you actually write in it every time, and fails entirely the week you forget. An app that records automatically removes the discipline problem, which is the real reason most logs fail rather than any rule about format.

The odometer readings people skip

Publication 463 asks for start and end of year odometer readings, and almost nobody has them. They support your total mileage figure and show that your business miles are a plausible share of the whole. Photograph the dashboard on 1 January and 31 December. It takes ten seconds and it strengthens the entire log.

How long to keep it

Three years from filing is the normal assessment window, six if there is any question of substantially understated income. Keep the records somewhere that survives a lost phone or a flooded truck, which in practice means something backed up rather than only a notebook.

The 2026 rates you apply to those miles are on the IRS mileage rate page, and they changed halfway through the year.

Sources

IRS Publication 463, which is where the record keeping rules actually live
IRS standard mileage rates

This is general information, not tax advice. Check with an accountant about your own situation before filing.

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