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Lodgya blog · 2 November 2026
Car Logbook for Tax: ATO Rules, Records and a Simple Template
What the ATO wants in a car logbook for tax: the 12 week rule, odometer records, trip purposes, a simple template and how it compares to cents per km.
4 min read
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General information only, not tax advice. This article doesn't take your personal circumstances into account, and tax rules change each income year. Check the ATO website or speak to a registered tax agent before acting on it. Lodgya is a record-keeping tool and is not a registered tax agent. See our disclaimer.
If you use your own car for work, a car logbook for tax is usually the difference between a small deduction and a much better one. The logbook method lets you claim the business-use percentage of your actual running costs instead of a flat rate per kilometre. That sounds generous, and it can be, but only if your records stand up to scrutiny.
Here is what the ATO expects, what goes in the book, and a plain template you can copy today.
How a car logbook for tax works
You record your driving over a set period, work out what share of those kilometres were for business, then apply that percentage to your total car costs for the year. Costs can include fuel, servicing and depreciation. You still need receipts for the car expenses themselves, because the percentage is applied to real figures, not guesses.
The calculation is simple:
Business use percentage = business kilometres divided by total kilometres, multiplied by 100.
So if your 12-week logbook shows 1,000 km of driving and 400 of those were business, your business use percentage is 40 per cent. You then claim 40 per cent of your running costs for the year.
What your logbook must show
A valid logbook covers at least 12 continuous weeks. You cannot stitch together a week here and a week there. You also need to record the period itself and every business trip inside it.
The start and end dates of the logbook period
Odometer reading at the start of the period
Odometer reading at the end of the period
Total kilometres travelled during the period
For each business trip: the date, start odometer, end odometer, kilometres travelled and the purpose of the trip
On top of the logbook, keep receipts for your car costs. A logbook without receipts is half a claim.
A logbook is valid for up to five years, as long as your driving pattern stays similar. If your work use changes a lot, for example you move to a different site or stop doing client runs, start a fresh logbook rather than coasting on an old one.
A simple logbook template
Start with a cover block for the period, then record each business trip as it happens.
Logbook period field | Your entry |
|---|---|
Start date | |
End date | |
Odometer at start | |
Odometer at end | |
Total kilometres |
Date | Trip purpose | Odometer start | Odometer end | Kilometres |
|---|---|---|---|---|
Write the purpose so a stranger could understand it. "Site inspection at Brunswick job" tells the story. "Business" on its own does not.
Logbook method vs cents per km
The cents per km method is simpler. You multiply your business kilometres by the current ATO rate, and your claim is capped at 5,000 business kilometres. You do not need a logbook, but you do need to show how you worked out the kilometres. Check the ATO website for the rate that applies to the income year you are claiming.
Method | What you need | Best fit |
|---|---|---|
Logbook | 12 continuous weeks of records plus receipts for car costs | Higher business use or a costly car to run |
Cents per km | Business kilometres, capped at 5,000 | Low business use and simple record keeping |
The ATO has the full rules on its motor vehicle expenses page, including how the logbook method is applied.
Mistakes that cost people money
Rebuilding the logbook from memory in June instead of recording trips as they happen
Leaving the period start and end odometer readings blank
Recording personal trips but not logging total kilometres, which makes the percentage impossible
Losing fuel and servicing receipts, so there is nothing to apply the percentage to
Keeping an old logbook running after a big change in how the car is used
Tracking it without the shoebox
Paper works, but it is easy to fall behind. Lodgya's free logbook tool at lodgya.com.au/logbook tracks your trips, keeps an eye on the 12 week period and calculates your business use percentage as you go. It runs in the browser, so there is nothing to install before your next job.
Frequently Asked Questions
How long does a car logbook last for tax?
Your logbook stays valid for up to five years from the end of the income year you first used it, provided your driving pattern stays similar. If your work-related use changes significantly, such as a new job with different travel, you should start a new logbook covering at least 12 continuous weeks.
Does the 12 week period have to be continuous?
Yes. The ATO expects the logbook to cover at least 12 continuous weeks. You cannot add up scattered weeks across the year to reach the total. Pick a period that reflects your normal driving, ideally one that includes your typical mix of work and personal trips.
Do I need receipts if I keep a logbook?
Yes. The logbook sets your business use percentage, but you still need receipts or records for the car costs you are claiming, such as fuel and servicing. The percentage is applied to those documented costs, so keep the paperwork alongside the logbook rather than relying on the logbook alone.
Can I switch between the logbook and cents per km methods?
You choose one method per car per income year, and the choice can change from year to year. Many people use cents per km while their business use is low and switch to a logbook once their work kilometres climb. Check your own situation with a registered tax agent before deciding.
This article is general information only and is not tax advice. Confirm your circumstances with the ATO or a registered tax agent.
