How to Keep an ATO-Compliant Car Logbook (Without the Pain)
The 12-week logbook that unlocks five years of bigger car deductions
For anyone who drives a lot for work — drivers, tradies, reps, mobile freelancers — the car logbook is the single most valuable piece of paperwork you'll ever keep. It's the difference between the cents-per-km cap (a maximum of 5,000km) and claiming your real, uncapped business-use percentage of every cost.
The good news: you only have to do it properly once every five years.
General information only, not personal tax advice. Verify current logbook rules and rates with the ATO (ato.gov.au).
Why bother? Because the cap is brutal for high-km drivers
The cents-per-km method is capped at 5,000 business kilometres. Drive 25,000 work kilometres and you're still stuck at the cap — leaving thousands unclaimed. The logbook method has no cap: you claim your business-use % of actual fuel, servicing, rego, insurance, interest and depreciation. For most heavy drivers, that's two to three times more.
Step 1 — Run the logbook for 12 continuous weeks
Pick a representative 12-week stretch that reflects your normal driving. It must be continuous.
Step 2 — Record every trip (business AND private)
This is where people go wrong: you log every trip, not just work ones, because the ATO needs both to calculate your business percentage. For each trip record:
- The date
- Start and finish odometer readings
- Kilometres travelled
- The purpose (e.g. "client meeting, Parramatta")
Step 3 — Calculate your business-use percentage
At the end of 12 weeks: business km ÷ total km. If you drove 6,000km total and 4,500 were for work, that's 75% business use. That percentage then applies to all your car costs for the year.
Step 4 — Keep your expense receipts
Hold onto receipts for fuel, servicing, tyres, rego and insurance, plus your loan/lease and depreciation details. You claim your business % of the total.
Step 5 — Reuse it for five years
A valid logbook lasts five years unless your circumstances change materially (new job, moved house, very different driving pattern). One good 12-week effort, five years of bigger deductions.
The traps
- Only logging work trips. Invalidates the whole logbook — you need total km too.
- Counting the commute. Home to your regular workplace is private, not business.
- An out-of-date logbook. Older than five years (or after a big change) = no longer valid.
- Claiming actual costs with no logbook at all. Then you're limited to cents-per-km.
How TaxBot does the hard part
Keeping a paper logbook for 12 weeks is exactly the kind of task people abandon by week two. TaxBot tracks your trips and helps you tag each as business or private, builds the ATO-compliant logbook for you, captures your fuel and service receipts, and shows your business-use percentage in real time — so the deduction is ready, not reconstructed.