What happens if the IRS questions your mileage deduction
They ask you to prove it, and the burden is entirely yours. Publication 463 is explicit that to deduct car expenses you must be able to prove the elements of the expense — the amount, the time and place, and the business purpose — and that documentary evidence written at or near the time of the trip carries more weight than something assembled afterwards. If you cannot produce a record that meets that bar, the deduction can be reduced or disallowed even if you genuinely drove every mile.
For a gig driver this is not an abstract risk, it is the whole reason the log matters. Miles you drove but did not record are, for tax purposes, miles you did not drive.
The four elements you have to be able to show
Publication 463 frames adequate records for car expenses around a small, specific set of facts. In practice, for each business trip you want:
- The date. Non-negotiable, and in 2026 doubly so because the year has two mileage rates split at June 30.
- The mileage. Business miles for that trip. Odometer readings are the gold standard but a recorded trip distance is normally accepted.
- The destination or route. Where you went. For delivery work, the drop area or the platform's own trip reference is usually enough.
- The business purpose. Why the trip was business. "DoorDash delivery," "Uber fare," "drove to hotspot while online" are all legitimate purposes; the point is that it is recorded rather than assumed.
Alongside the per-trip record you also want the total miles the vehicle was driven in the year and the business-use percentage, because both appear on the return and both are questions an examiner asks early.
What "adequate records" actually looks like
There is no IRS-approved app and no required format. A log qualifies on content, not on packaging. All of these can be adequate:
- A written mileage notebook filled in at the end of each shift
- A spreadsheet with one row per trip
- An app export listing every trip with date, distance, destination and purpose
- A calendar with per-day entries and odometer readings
And all of these are not, on their own:
- A single annual total with no per-trip breakdown
- A round number
- A dashboard screenshot showing a summary figure
- A reconstruction from memory with no supporting evidence
- Bank statements alone, which show fuel purchases but not business miles
The format is not the test — completeness and timing are. A shoebox of dated index cards written each night beats a beautiful app export that was reverse-engineered in April.
Reconstruction: what it can and cannot do
Drivers frequently arrive at this problem having already driven most of the year untracked. Reconstruction is a legitimate answer, with real limits.
What makes a reconstruction credible is independent evidence that pins your driving to specific dates. The strongest sources, roughly in order:
| Evidence | What it proves | Strength |
|---|---|---|
| Platform trip/delivery history | You worked, on these dates, in these areas | Strong |
| Odometer readings (service records, inspections, photos) | Total distance between two dated points | Strong |
| Fuel and charging receipts with dates and locations | You were driving, and roughly where | Moderate |
| Bank and platform deposit records | You earned on these dates | Moderate |
| Calendar entries, texts confirming shifts | You intended to work then | Weak on its own |
| Memory | Nothing | None |
What a reconstruction cannot do is invent precision it does not have. If your platform history shows 180 deliveries in March and your only odometer points are January and December, you can build a defensible estimate for March — but you should build it transparently, document the method, and keep the underlying evidence with the return.
The honest advice: reconstruct the past from evidence, and start tracking today so the rest of the year is contemporaneous. A year that is half reconstructed and half properly logged is far stronger than a year that is entirely estimated. See what to do if you did not track your miles.
Why gig drivers get asked more often than they expect
Nothing about gig work makes an examination inevitable, but three features of the category make mileage a natural question.
The deduction is large relative to income. A driver with $38,000 of gross platform earnings and a $15,000 mileage deduction is claiming that roughly 40 percent of revenue went to driving. That is entirely normal for the work and entirely reasonable to ask about.
The income is fully reported. Platforms file 1099-NEC and 1099-K forms, so your revenue is already known. The deduction side is the only variable.
The records live on someone else's server. Drivers who never exported their platform history and then lost account access have no evidence at all. Export yours annually; treat it as part of filing.
Building a log that survives a question
- Record contemporaneously. Whatever tool you use, the record should be created the same day. This is the single biggest factor in how much weight it carries.
- Keep dates on every row. A total without dates cannot be split at June 30, cannot be matched to platform history, and cannot be corroborated by anything.
- Classify honestly. A log containing personal trips marked as personal is more credible than one containing only business trips. It shows the classification actually happened.
- Reconcile to the odometer. Photograph the odometer on January 1 and December 31. Two photographs a year turn your total into a bounded, checkable figure.
- Export and archive your platform history at least annually, and store it with the log.
- Keep parking and toll receipts separately. Publication 463 treats business parking fees and tolls as deductible in addition to the standard mileage rate, so they are a separate line and a separate pile of evidence.
- Keep the records for at least three years after filing, longer if you want margin.
Where MileTruth fits
MileTruth is built so that the artefact you can hand to a preparer or an examiner is the default output rather than a feature you have to find: a dated, per-trip log with distance, classification and purpose, exportable as PDF and CSV, pre-split at the June 30 rate boundary, reconcilable against your odometer, and complete because the capture engine is designed around not losing trips in the first place.
That is the same output every serious tracker should produce. The difference this year is that 2026's two rates make a dateless log unusable, and the difference in this category is that a log is only as good as the trips that made it in.
This page is general information, not tax or legal advice. It cites IRS publications so you can read the source yourself. Your circumstances may differ, and if your return is examined you should speak to a tax professional.
Questions and answers
What records does the IRS want for a mileage deduction?
Under Publication 463 you must be able to prove the amount of the expense, the time and place of the travel, and its business purpose. For car expenses that means the date of each trip, the business miles driven, the destination or route, and the business reason.
Does the IRS require a contemporaneous mileage log?
The IRS does not require a specific format, but it states that a record made at or near the time of the expense has more value than one written up later, because the facts are fresh. A reconstruction supported by independent evidence is acceptable; a bare estimate is not.
Can I use my DoorDash or Uber trip history as a mileage log?
Platform histories are strong supporting evidence but generally not a complete log on their own, because they typically record only the paid portion of your driving and not the unpaid miles to a pickup or between offers. Use them as corroboration alongside your own record.
What happens if my mileage records are rejected?
The deduction can be reduced or disallowed, which raises taxable income and therefore tax, and interest accrues from the original due date. Penalties may also apply. The practical result is that unrecorded miles are worth nothing regardless of whether you drove them.
How long should I keep my mileage records?
Keep records supporting an item of income or a deduction until the period of limitations for that return runs out, which is generally three years from filing, and longer in specific circumstances. Many drivers keep seven years of logs because storage is free.
MileTruth. “What happens if the IRS questions your mileage deduction.” Baker Ventures LLC, September 6, 2026. https://miletruth.bakerventuresstudio.com/why/what-happens-if-the-irs-questions-your-mileage/