Guide
The IRS is asking for your mileage log. What do you hand over?
A letter arrives about a return you filed a year or two ago, and the item it questions is the car: the business miles on Schedule C, or on the form your preparer filled in for you. The IRS wants to see what the number rests on. This guide covers what it asks you to prove, what its own publication says when your records are not complete, and how to put the evidence together from what your phone recorded at the time.
Before anything else: note the deadline on the letter and the tax year it names. An examination is a good moment to get help from an enrolled agent or a CPA, who can also speak for you. Nothing here is tax advice; it is about getting the records in order.
What the IRS asks you to prove
IRS Publication 463 lists four elements for each business use of a car:
| Element | What it means for mileage |
|---|---|
| Amount | The business miles of each use, and the total miles you drove the car in the year |
| Time | The date of each use |
| Place | Your business destination |
| Business purpose | Why the drive was for work |
The total miles for the year matters as much as the business miles: it is what the business share is measured against. Service invoices, inspection reports and the odometer reading on a sale or trade-in all carry dated mileage, and two of them a year apart give you the total.
If you kept a log, and if you did not
If you kept a log, that is what you hand over. The publication says each element should be recorded "at or near the time of the expense or use", and that a timely record "has more value than a statement prepared later".
If you did not, the deduction is not automatically gone. For an element you cannot show from complete records, Publication 463 asks for two things together:
- "Your own written or oral statement containing specific information about the element", and
- "Other supporting evidence that is sufficient to establish the element."
That second part is where GPS history earns its place. Google Maps Timeline recorded the date, the route and the distance of each drive while you drove it. A statement built on that record is specific, and the record itself is the supporting evidence.
The publication also allows records kept for only part of the year, if other evidence shows that period is "representative of the use throughout the tax year". A few complete months can stand for the year, if other evidence shows they are typical.
Does your phone still hold that year?
An examination usually looks at a return filed one or two years ago, so the drives you need are older than people expect. Where they can still be:
- On the phone, if Timeline was on and auto-delete was not left at three months. Open Google Maps, tap your profile picture, then Your Timeline, and go to a day in that year.
- In an old Takeout archive, for years before Google moved Timeline onto the phone in 2024: request one from Takeout, or look for one you downloaded back then. Takeout holds nothing recorded after the move.
- On an old phone you still have in a drawer, if you changed handsets since.
If none of them has it, the history cannot be rebuilt from Google, and the evidence has to come from elsewhere: calendars, invoices to clients, delivery platform summaries, fuel receipts. Why Timeline history goes missing explains the cases where it is gone for good.
Put the file together
- Export the history from the phone, or find the Takeout archive. The export guide covers both.
- Open it in Time-mile and pick the year the letter names. Several files load together: an old archive and a recent phone export merge into one table.
- Find the addresses (Premium), so each drive shows where it started and ended rather than coordinates. In the settings, the address format can be set to the full address.
- Take out what was personal. Hide a drive with the eye at the end of its row. Click a start or end place to say what it is (home, a personal place, a business place), and the answer covers every drive that stops there.
- Export the PDF report. It lists each drive with its date, route and distance, and works out the deduction at the IRS rate in force on each drive's date. Keep the CSV too, for whoever is handling the examination.
Then add the business purpose in your own words, as the publication asks: which client, which job, which delivery platform. Hand over the log with the original export file and whatever confirms the purpose (invoices, a calendar, platform earnings statements). If the rebuilt total comes out lower than the figure you filed, say so rather than defend the old number; the IRS has seen both.
How long to keep all this
Publication 463 says to keep the records supporting a deduction for 3 years from the date you file the return, and longer for records of the car's business use while you are still depreciating it. Once this is sorted out, set Timeline's auto-delete to 36 months and export the history once a year, so the next request finds a record already waiting.
Rebuild the year the IRS is asking about
Load your Timeline and see the year before you pay anything. Runs in your browser.
Launch Time-mileFrequently asked questions
How do I prove my mileage to the IRS without a log?
Publication 463 asks for your own written or oral statement containing specific information about each element, together with other supporting evidence sufficient to establish it. Google Maps Timeline history, recorded by GPS as you drove, gives the dates, routes and distances; invoices, calendars and platform summaries support the business purpose.
Is a mileage log rebuilt later accepted in an audit?
The IRS gives most weight to records made at or near the time of the drive. A log written from memory at filing time is the weakest kind. A log rebuilt from GPS history is different: the underlying record was made at the time, and the original export file shows it. Whether it is enough for your case is for the examiner to decide.
How far back can I rebuild mileage from Google Timeline?
As far back as the history still exists. On the phone, that depends on the auto-delete setting, which defaults to three months for anyone who turned Timeline on after its move to the device. Years before the 2024 move to the phone may still come out of Google Takeout, or from an archive you downloaded back then.
What else does the IRS want besides business miles?
The total miles you drove the car during the year, the date of each business use, the destination, and the business purpose. Service invoices and inspection reports that note the odometer reading help establish the total.
How long should I keep mileage records?
Publication 463 says to keep records supporting a deduction for 3 years from the date you file the return, and to keep records of the car's business use for each year of its recovery period if you depreciate it.