Glossary

Mileage Log

The contemporaneous record §274(d) requires. Four elements per trip, kept at or near the time of the drive. Phone notebooks fail; auto-logged GPS records win.

A mileage log is the contemporaneous record of business vehicle use that the tax code requires to support any car-and-truck deduction. The legal authority is IRC §274(d) and Temp. Treas. Reg. §1.274-5T(c); the practical playbook is IRS Publication 463.

The four elements per trip (and per Pub. 463):

  1. Date of the trip
  2. Business miles driven (or starting/ending odometer)
  3. Route or destination (address, client name, store)
  4. Business purpose — concretely, not “errands”

Plus two annual numbers Schedule C Part IV demands: total miles for the year (so the business-use percentage can be computed) and the date the vehicle was placed in service.

Timing matters. The regulation requires the log to be “made at or near the time of the expenditure or use.” A weekly log is explicitly accepted as “near the time” (Temp. Reg. §1.274-5T(c)(2)(ii)(C)). A spreadsheet built every April from credit-card statements and Google Maps is not contemporaneous and is routinely rejected.

What works in court. Electronic logs from a GPS-based mileage app are accepted when they capture the four elements and were generated contemporaneously. The Tax Court explicitly accepted a MileIQ-generated log to support a real-estate agent’s standard-mileage deduction in Chappell v. Commissioner, T.C. Summ. Op. 2024-2. The court found the contemporaneous app records sufficient to satisfy §274(d) even when other categories of records failed.

What fails in court. Reconstructions, calendars, and iPad notes:

  • Velez (T.C. Memo. 2018-46) — iPad calendar entries + reconstructed log = $0 deduction + 20% penalty.
  • Garza (T.C. Memo. 2014-121) — calendar with no business purpose noted = $20,085 deduction lost.
  • Khan (T.C. Summ. Op. 2025-5) — generalized explanations and reconstructed spreadsheets = no deduction; the Cohan rule does not apply.

Worked example — a defensible entry.

Date: April 3, 2026
Vehicle: 2022 Toyota Camry
Start: 14227 mi (home, 6:42 AM)
End: 14269 mi (DoorDash dash zone, Plano TX, 7:18 AM)
Miles: 42
Purpose: Drive to Plano dash zone for lunch shift (DoorDash)

Repeat for every trip. An ADT-based app does this automatically.

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