General tax education, not tax advice. This page describes how IRS correspondence about vehicle expenses generally works for U.S. federal Schedule C filers. It is not legal, tax, or accounting advice, and nothing here promises any outcome. Notice numbers, deadlines and procedures change; read the notice you actually received and have a licensed professional review anything where the records are thin or the amounts are large.
The envelope is thinner than you expect. Somewhere in it is a line saying the vehicle expense on your Schedule C is being questioned, and a date.
The useful thing to understand in the first hour is that this is a request for documents, not a verdict. Nobody has decided you were wrong. Someone has asked you to show the records the deduction was always supposed to rest on. If you have them, this is administrative. If you do not, it is a harder conversation — but even then, the worst move available is silence.
First: work out which letter you got
The notice number is printed in the top right corner, and it changes what you are answering.
A CP2000 is not a mileage question at all. It is an automated proposal generated when the income reported on your return does not match the 1099s and W-2s the IRS already holds. For gig drivers this is common and often has an easy explanation — a 1099-K counted gross fares including the platform’s cut, say. Read the 1099-K versus 1099-NEC guide before you reach for the mileage log, because the log may be irrelevant to the letter in your hand.
A correspondence examination is the one about your driving. It is conducted by mail, usually covers one or two line items rather than the whole return, and it asks for substantiation of car and truck expenses. The request often arrives with a form listing exactly which documents are wanted. That list is the assignment; answer it literally.
Diary the response date today. Notices print a date to respond by, commonly thirty days out. Missing it is what turns a document request into a proposed assessment you then have to argue backwards out of. If the records will take longer than that to gather, call the number on the notice before the date passes and ask for more time. Requests made in advance are routine; explanations offered afterwards are not.
What a mileage question is actually asking for
For a passenger automobile, the substantiation described in Publication 463 and Treas. Reg. 1.274-5T is per-trip and specific. For each business trip: the date, the miles driven, the destination, and the business purpose. Plus enough information about the vehicle’s total use for the year that the business percentage can be checked.
Read that list against whatever you have. Most people discover they have two of the four. Platform histories give dates and often distances, but no purpose and none of the miles driven between gigs or on the way to a zone. A bank statement proves you bought fuel, which is not evidence of a business mile.
If what you have is genuinely complete, the response is short: a cover letter, the log, and the corroboration below. Cases where a complete contemporaneous log is produced tend not to become arguments, because there is nothing left to argue about.
The corroboration that goes around the log
Supporting evidence does not replace a log — that is worth being blunt about — but it makes a log credible, and it is what turns a reconstruction from a guess into something defensible.
- Odometer readings at the start and end of the year. These establish total miles, which is what the business percentage is measured against. A photo with a visible date is better than a number written down later.
- Dated service and inspection invoices. Garages routinely print the odometer reading on the invoice. Two invoices eight months apart are an independent record of how far the car travelled between them, created by someone with no stake in your return.
- Platform trip histories. Download them for the year in question while you still can. They corroborate that you were working on the days your log says you were.
- Calendars, appointment books, client lists. For non-platform driving, these are what establish purpose.
The thing people hope is true, and is not
There is a widely repeated idea that if records are missing, a reasonable estimate will be accepted — the Cohan approach, named for a 1930 case about a Broadway producer’s expenses.
It does not apply here. A passenger automobile is listed property, and the substantiation requirements for listed property were written specifically to exclude estimation. This is the single most important thing to understand before you respond, because it determines whether you are assembling a defence or negotiating a position.
That does not mean a rebuilt log is worthless. It means a rebuilt log is weaker evidence than a contemporaneous one and should be presented honestly as what it is, with the corroboration above doing as much work as possible. If that is where you are, the reconstruction guide covers how to build one and what its limits are.
How to actually send it
- Respond in writing, to the address on the notice, referencing the notice number on every page.
- Send copies. Never originals. You may need them again.
- Use a method that gives you proof of delivery, and keep that proof with a complete copy of the package you sent.
- Answer the question asked and stop. Volunteering unrelated records invites unrelated questions.
- Include a short cover letter listing what is enclosed, in the order the request listed it.
If you disagree with the proposal, the notice will explain how to say so, and there are appeal routes beyond the first response. If matters progress to a statutory notice of deficiency, that document carries its own strict deadline to petition the Tax Court — a deadline that is not extendable. That is the point at which professional help stops being optional.
When to bring in a professional
Sending a complete log in response to a straightforward request is something many people handle themselves. Get a licensed professional involved when the log is thin or reconstructed, when the amounts are large relative to your income, when the letter questions more than the vehicle line, or when you intend to disagree. A tax professional can also be authorised to deal with the IRS directly on your behalf, which is worth something on its own if the correspondence is stressing you out.
What this means for next year
Every part of this is easier if the log already exists in the right shape. That is the whole argument for capturing trips as they happen rather than rebuilding them in April: not that it is more pleasant, but that it is the difference between answering a letter in an afternoon and spending a fortnight proving something you already knew.
TaxMiles keeps the log in the four fields a request asks for — date, miles, destination, purpose — and exports the year in a form you can hand to a preparer or attach to a response. It is a recordkeeping tool and nothing more: it does not file, does not represent you, is not affiliated with the IRS, and cannot create records for a year you did not track. What it can do is make sure this particular envelope is boring next time.
Frequently asked questions
Does a letter about car expenses mean I am being audited?
Check the notice number. A CP2000 is an automated income-matching proposal, not a mileage question. A correspondence examination is a limited review by mail, often of one or two line items. Neither is someone visiting your home, and both are answered with documents.
Can I estimate my mileage if I did not keep a log?
Not in the way people hope. Cars are listed property and the substantiation rules for listed property do not accept a reasonable estimate in place of records. A reconstruction is still worth assembling — it is simply weaker evidence, and should be presented as a reconstruction.
What if I miss the date on the notice?
The proposal generally proceeds without your side of it. Ask for more time before the date passes by calling the number on the notice. If a statutory notice of deficiency is eventually issued, its deadline to petition the Tax Court is strict and not extendable.
Do platform trip histories count as a mileage log?
On their own, no. They are strong corroboration — they establish that you worked on given days and often how far passengers or orders travelled — but they carry no business purpose and typically miss the miles between jobs. Download them anyway, for the year in question, while you still have account access.
Does TaxMiles deal with the IRS for me?
No. It is a mileage recordkeeping app, not a tax preparer or representative, and it is not affiliated with the IRS. It holds and exports the log; the response is yours or your professional’s.
Related reading: what an IRS-ready mileage log contains, reconstructing a log after the fact, how long to keep mileage records, 1099-K vs 1099-NEC, exporting the year for your CPA, and the odometer photo habit.
This article is general tax education for U.S. federal Schedule C filers, not legal, tax, or accounting advice, and not a guarantee of any deduction, refund, or examination outcome. Notice types, response windows, appeal routes, Publication 463, Treas. Reg. 1.274-5T and the listed-property rules can change; read the notice you received and the current IRS materials, or work with a licensed professional. TaxMiles: Mileage Tracker (App Store id 6758579463) is a mileage recordkeeping tool, not a tax preparer or representative. It is not affiliated with the IRS, and is not MileIQ, Everlance, or Mileage Tracker for Taxes (id 6758426140).