Year-End Mileage Checklist to Send Your Tax Clients

The single most useful thing a preparer can send a mileage-heavy client in December is a short checklist, sent before the year closes, not a request for numbers after it already has. A client who acts on this in the last week of December walks into their appointment with a clean file instead of a reconstruction project.

Source: IRS Publication 463, on the records needed to support a mileage deduction for the year.

1. Read the odometer on December 31, not "sometime in January"

The end-of-year odometer reading is the denominator for business-use percentage and it has to be as close to December 31 as possible. A reading taken three weeks into January, after more driving has happened, quietly overstates total annual mileage and understates the business-use percentage that gets applied to actual expenses.

2. Confirm the mileage log is complete through December 31

Ask the client to check their app or log for gaps: a dead battery week, a lost phone, a period auto-tracking was accidentally turned off. Better to identify and patch a two-week gap in late December than discover it during the appointment when the trips are no longer fresh in memory.

3. Flag any vehicle changes during the year

• A vehicle sold or traded in mid-year, which needs its own mileage log covering only the months it was owned
• A new vehicle placed in service, which triggers the first-year standard-vs-actual election discussed in standard vs actual mileage for clients with more than one vehicle
• A vehicle moved from personal to business use partway through the year

4. Pull 1099s and reconcile against income records

Every platform or client that paid the taxpayer $2,000 or more during the year issues a 1099-NEC under the current OBBBA threshold. Ask the client to gather these as they arrive rather than waiting for the appointment, and flag any client or platform that paid close to the threshold, since a missing 1099 from a smaller payer does not remove the income, it just removes the paper trail.

5. True up quarterly estimated payments

A December check-in is the last real chance to make a fourth-quarter estimated payment adjustment before the January 15 deadline. If mileage deductions came in lower than expected, or income ran higher, this is the moment to catch an underpayment before it becomes a penalty.

6. Ask about any new business use started late in the year

A client who took on a new side contract, added a second job with driving involved, or started a new business in October or November may not think to mention it unless asked directly, since it feels too recent to matter for "this year's taxes." Even two or three months of business mileage is worth capturing correctly rather than folded in vaguely with the rest of the year's driving, and it also flags a possible under-withholding or under-payment issue worth catching before January 15.

The one-paragraph version to actually send

"Before December 31: read your odometer and write it down, check your mileage log for any gaps and fill them in while you remember, note if you bought, sold, or started using a new vehicle for business this year, tell us about any new business use that started late in the year, and gather any 1099s you've already received. Bring all of it to our appointment." Short enough that a busy client actually reads it.

Why sending this in December beats asking at the appointment

Every item on this checklist gets meaningfully harder to answer accurately once the calendar flips. An odometer reading taken in December is exact; one estimated in February is a guess. A gap in the log noticed in December can still be patched from memory or corroborating records; the same gap noticed in March often cannot. Sending the checklist costs you five minutes and a template email. Not sending it costs your client a weaker number and costs you a longer, messier appointment.

When should this checklist actually go out?

The first or second week of December, early enough that clients can still act on it before the year closes, but close enough to year-end that it feels urgent rather than easy to set aside.

Should this go to every client or just self-employed ones?

Send it to anyone with meaningful business mileage on their return, self-employed or otherwise, including W-2 clients in one of the narrow Form 2106 categories covered in Schedule C vs. Form 2106 mileage after the TCJA.

Should the checklist go out by email, text, or a client portal?

Whichever channel that client actually reads. A checklist sent to a channel a client ignores accomplishes nothing; match the delivery method to how that specific client normally communicates with your office.

Why year-end is the wrong time to discover a tracking gap

A checklist run at year-end can catch missing months, unclear entries, or a rate-split error, but it cannot recreate mileage that was never captured in the first place with the same reliability as contemporaneous tracking would have. Year-end review is a safety net for catching problems, not a substitute for having captured the underlying data accurately across the year.

The most useful outcome of a year-end checklist, beyond fixing this year's return, is identifying which specific gaps recurred, a consistently missing category, a recurring reconstruction need, and using that pattern to fix the client's tracking setup before the next year starts, rather than running the same checklist next December against the same avoidable gaps.

The easiest way to make this checklist unnecessary next year: get clients on automatic tracking now. Try TruMile →

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