ATO Mileage Log Requirements: What Records Does the ATO Expect?

Cents-per-km: what written evidence must include

For the cents-per-km method, the ATO requires 'written evidence' for each business trip. Per ATO guidance at ato.gov.au, each record must include: the date of the trip, the destination or area of travel, the business purpose of the trip, and the kilometres driven.

You do not need receipts for fuel, insurance, or maintenance under the cents-per-km method. The rate (91 cents for 2026-27, up from 88 cents in 2025-26) is designed to cover those operating costs within the rate itself. The trip record is the primary requirement.

Written evidence can be a paper notebook, a spreadsheet, or an app-generated log. The ATO has no preference on format; the requirement is content.

Logbook method: what the 12-week record must include

For the logbook method, every trip during the 12-week representative period must be logged with: date, destination, business purpose, and odometer readings at the start and end of each trip (or the kilometres for that trip). You also need odometer readings at the start and end of the 12-week period to calculate total kilometres.

The 12 weeks must be consecutive and representative of your typical driving pattern. Do not run the logbook during an unusually quiet period or an unusually heavy one - the resulting business-use percentage will not reflect the full year.

For actual vehicle expenses, keep receipts for fuel, insurance, registration, maintenance, and repairs across the entire financial year. The ATO may request these on review.

Contemporaneous: what the ATO means

The ATO expects records to be made 'at or near the time' of the trip. Filling in a month's trips from memory at month-end is not contemporaneous. End-of-year reconstruction from a calendar is not contemporaneous.

Auto-tracking apps that log trips in real time satisfy the contemporaneous requirement. The app records the date, start and end points, and kilometres automatically. You add the business purpose before moving on to the next trip - typically less than 30 seconds of input per trip.

The ATO's record-keeping guidance is published at ato.gov.au under 'Keeping tax records.'

How long to keep car expense records

The ATO requires records to be kept for five years from the date you lodged the tax return they relate to. If you lodge your 2025-26 return in October 2026, keep car expense records until at least October 2031.

If the ATO opens a review or audit, the obligation extends until the matter is resolved. A logbook that covers a five-year validity period should be retained until five years after lodgement of the last return it supports.