Australian ATO Vehicle Logbook Guide: 12-Week Period, Odometer Rules & 91c/km Method

1. The Two ATO Car Deduction Methods Explained

For eligible cars in Australia, sole traders and individuals generally choose between the Cents per Kilometre method and the Logbook method.

Under the Cents per Kilometre method (configured at 91 cents per km for 2026–27), you can claim up to a maximum of 5,000 business kilometres per car per income year. This single rate already covers fuel, registration, insurance, servicing, and depreciation — so those running costs cannot be claimed a second time on top of the cents/km calculation.

• Cents per KM (2026–27): 91c/km up to 5,000 eligible business km per car (no separate fuel/rego double-counting).
• Logbook Method: Claim the business-use percentage of actual eligible vehicle expenses based on a valid 12-week continuous representative logbook.
• Vehicle Eligibility: Standard cents/km car rules apply to cars; vans over 1 tonne payload, motorcycles, and scooters have distinct rules and should not silently use car cents/km caps.

2. What a Complete 12-Week ATO Logbook Requires

To rely on the ATO logbook method, your logbook must cover a minimum continuous 12-week period that is representative of your travel throughout the year. Each vehicle requires its own separate logbook.

• Start date and end date of the 12-week continuous logbook period.
• Odometer readings at the start and end of the logbook period.
• Income-year opening and closing odometer readings (1 July to 30 June).
• For each business journey: date, start/end odometer (or tracked distance with odometer verification), kilometres travelled, and a clear business purpose.
• Calculated business-use percentage (Business KM ÷ Total KM × 100).

3. Avoiding Common Logbook Mistakes

Never automatically classify every detected trip as business travel. Private errands and ordinary home-to-regular-workplace commutes must remain private so your business-use percentage stays accurate and defensible.