If you use your car for work, the ATO logbook method lets you claim a higher deduction than the cents per kilometre method — but only if you keep the right records. Understanding ATO logbook requirements upfront saves you from a rejected claim at tax time.
This guide covers everything you need: what the ATO expects, how the 12-week period works, what each trip entry must include, and the mistakes that catch people out.
What the ATO requires in a logbook
A valid logbook must be a continuous written record of your car use across at least 12 weeks. The ATO does not prescribe a specific format, but every entry must capture certain details (covered below).
Your logbook establishes the business-use percentage of your vehicle. That percentage is then applied to your actual car expenses — fuel, insurance, registration, servicing, and depreciation — to determine how much you can claim.
The logbook must relate to the same car for the full 12-week period. If you change vehicles, you need a new logbook for the new car.
The 12-week logbook period explained
The 12-week period must be continuous — you cannot pick your 12 best weeks and piece them together. The period should also be representative of your typical driving pattern throughout the year.
You can start the 12-week period at any point during the income year. Many people begin in July so the logbook covers the start of the financial year, but there is no rule requiring this.
Once completed, a logbook is valid for five years, provided your business-use pattern does not change significantly. If your work travel changes — for example, you take on a new job with different travel demands — you should complete a new logbook.
What to record for each journey
Every trip in your logbook needs the following information:
- Date of the trip
- Odometer reading at the start of the trip
- Odometer reading at the end of the trip
- Kilometres travelled (end minus start)
- Reason for the trip — enough detail to confirm it was work-related
- Whether the trip was business or private
“Went to work” is not a sufficient reason. A clear description like “client meeting at 52 Collins Street” or “delivery to Sunshine warehouse” gives the ATO what it needs to verify the claim.
You also need to record the odometer reading at the start and end of the 12-week period, plus the total kilometres for the year.
Apps like Tripbook automatically capture the date, distance, and start/end locations for every trip, making it straightforward to add a trip purpose and flag each journey as business or private.
How long is a logbook valid?
A logbook is valid for five income years from the year it was completed. You do not need to redo the 12-week period every year — but you must keep the original logbook and continue recording your odometer reading at the start and end of each income year.
The five-year rule applies as long as:
- You are using the same vehicle
- Your business-use percentage has not changed significantly
- The logbook was completed correctly in the first place
If any of those conditions change, start a fresh logbook. It is also good practice to redo the logbook voluntarily if your travel pattern shifts noticeably.
For a broader overview of the two main methods, see our ATO car expense guide.
How to calculate your business-use percentage
Once your 12-week logbook is complete, add up the kilometres for all business trips and divide that by the total kilometres driven during the period.
For example: 3,200 business kilometres out of 5,000 total kilometres = 64% business use.
That percentage then applies to your total car expenses for the full income year. If you spent $12,000 on the car and your business-use percentage is 64%, you can claim $7,680.
You need odometer readings at the start and end of the income year to calculate total annual kilometres. Keep a note of these — 1 July and 30 June are the key dates.
Common logbook mistakes to avoid
Starting and stopping the 12 weeks. The period must be continuous. Taking a two-week break in the middle and resuming is not valid.
Vague trip purposes. “Work trip” or “business” is not enough. Record the specific reason, client name, or destination.
Missing odometer readings. If you forget to record readings for a trip, do not estimate. The ATO may disallow your claim if entries look approximated.
Not keeping the logbook. The original document must be retained for five years after you lodge the tax return for the year you used it. A photocopy or scan is acceptable only if the ATO is satisfied it is accurate.
Forgetting private trips. Every trip — business and private — must be logged during the 12-week period. Leaving out private trips inflates your business-use percentage, which is a form of false claiming.
Using a new car without a new logbook. If you replaced your vehicle and started using the new one for work, the old logbook does not transfer.
If you are doing the kilometres tracking manually, see our guide on keeping an ATO-compliant kilometre log for a step-by-step approach.
Staying on top of ATO logbook requirements
Meeting ATO logbook requirements comes down to consistent record-keeping during the 12-week period and careful storage of your records afterwards. The most common errors — vague descriptions, missing odometer readings, and non-continuous periods — are all avoidable with a bit of discipline.
Tripbook makes the process easier by logging each trip automatically in the background. You review each journey, add the purpose, and mark it business or private. At the end of the 12 weeks, your records are ready to use.
