ATO Logbook Requirements: The 12-Week Car Logbook Explained

Short answer: An ATO logbook records every journey in your car for at least 12 continuous weeks: odometer readings at the start and end of each trip and of the whole period, the kilometres travelled, and a real business reason for each work trip. Business kilometres divided by total kilometres gives your business-use percentage, which you apply to your actual car costs. One logbook stays valid for five years if your driving pattern holds, but you still record odometer readings at the start and end of each later income year.

The rules below come from the ATO’s logbook method for business and apply to sole traders claiming for a car in the 2025–26 income year (the return most people are lodging now) and in 2026–27. The other way to claim, cents per kilometre, needs no logbook but caps the claim; cents per km versus the logbook compares the two in depth, and expenses and receipts for sole traders covers your other deductions.

What is an ATO logbook, and who can use the logbook method?

An ATO logbook is the record that proves what share of your car’s use was for business. It sets a percentage; your deduction is that percentage of what the car actually cost to run.

Sole traders and partnerships can choose between cents per kilometre and the logbook method, but only for a car: a motor vehicle, including a four-wheel drive, designed to carry a load of less than one tonne and fewer than nine passengers. A one-tonne ute or a heavier van is outside that definition, so neither method applies; the ATO’s deductions for motor vehicle expenses page covers those vehicles. Check the load rating before you start.

What does the ATO require in a logbook?

Every logbook needs the same core details, and leaving one out weakens the whole claim.

What	What to record
The car	Make, model and registration number
The logbook period	Start and end dates: at least 12 continuous weeks
Odometer for the period	Readings at the start and end, and total kilometres travelled
Each journey	Start and end date, odometer readings at the start and end, kilometres travelled, and the reason for the journey
The result	Your business-use percentage for the period
Each later year	Odometer readings at the start and end of every income year you rely on the logbook

Three details catch people out:

• The reason has to describe the trip. The ATO says “business” or “miscellaneous business” is not enough. “Quote for switchboard upgrade, 14 Hill St, Belmont” is.
• Write it as you go. Make entries at the end of the trip or as soon as reasonably practicable afterwards, in English.
• The 12 weeks must be representative of your travel across the whole year. Logging the weeks you spent on an out-of-town contract gives a percentage the rest of your year won’t support.

What does a filled-in logbook look like?

Here is the start of a page for an electrician driving a 2021 Mazda CX-5, with a logbook period from Monday 2 March 2026 to Sunday 24 May 2026.

Date	Odometer start	Odometer end	Km	Reason for the journey
Mon 2 Mar 2026	41,880	41,902	22	Electrical wholesaler, Moolap, to 14 Hill St, Belmont: quote for switchboard upgrade
Mon 2 Mar 2026	41,902	41,931	29	14 Hill St, Belmont, to 9 Bay Rd, Newtown: install downlights, job 031
Mon 2 Mar 2026	41,931	41,945	14	Private: supermarket and school pick-up
Tue 3 Mar 2026	41,945	41,983	38	Newtown to building site, Armstrong Creek: kitchen rough-in, job 029

Logging private trips too, marked “Private”, makes the log add up to the change in the odometer, so a missed trip shows up straight away. The summary at the end: odometer 41,880 on 2 March and 48,280 on 24 May, 6,400 km in total, 4,160 km of it business.

How do I work out my business-use percentage?

Divide business kilometres for the logbook period by total kilometres for the period, then multiply by 100. For the electrician: 4,160 ÷ 6,400 × 100 = 65%.

That percentage applies to the car’s actual costs for the income year. Suppose the car was owned for all of 2025–26:

Cost for 2025–26	Amount
Fuel	$4,100
Registration and insurance	$2,240
Servicing and tyres	$1,400
Loan interest	$1,200
Decline in value (depreciation)	$3,800
Total	$12,740

The logbook claim is 65% × $12,740 = $8,281. If the car did 26,000 km over the year, roughly 16,900 of those were business, but cents per kilometre stops at 5,000 km: 5,000 × 88 cents = $4,400 for 2025–26. With that much business driving, the logbook earns its keep.

How long is an ATO logbook valid, and when do you need a new one?

Each logbook is valid for five years, and you can start a new one at any time. In the later years you don’t redo the 12 weeks, but you do record odometer readings at the start and end of each income year.

Situation	What the ATO expects
Driving pattern unchanged	Keep using the logbook for up to five years
Your work changes, you take a new job, move house, or your pattern of use changes	Keep a new 12-week logbook
You replace the car and want to keep the old logbook	A written nomination before you lodge, stating you are replacing the original car with the new one and the date it takes effect
Two or more cars used for business	A logbook for each car covering the same period, representative of all of them
Business use started less than 12 weeks before 30 June	Continue the logbook into the next income year until it covers 12 continuous weeks

The change-of-circumstances and replacement-car rules are in the ATO’s logbook check-in guidance. If you are unsure whether a change counts, a fresh 12 weeks removes the doubt.

Logbook or cents per km: which should you use?

Use cents per kilometre when business driving is low or the car is cheap to run; use the logbook when you drive well over 5,000 business kilometres or the car is expensive to own.

	Cents per kilometre	Logbook
Claim	Business km × the year’s rate	Business-use % × actual car costs
Rate	88c per km for 2025–26; 91c per km for 2026–27	No set rate
Cap	5,000 business km per car per year	No cap
Records	Show how you worked out your business km	12-week logbook, yearly odometer readings, expense records

The ATO’s cents per kilometre determination explains that the 2026–27 rate of 91 cents is a base rate of 89 cents plus a one-off 2-cent uplift for that year only. A quick test: divide total yearly car costs by total kilometres. If the result is above the cents per km rate, the logbook generally claims more.

What receipts does the logbook method still need?

The logbook sets the percentage; you still need evidence of the costs. Under the ATO’s logbook method guidance:

• Receipts for registration, insurance, lease payments, servicing, tyres, repairs, electricity and interest charges.
• Fuel and oil: receipts, or a reasonable estimate based on odometer readings for the period you owned the car, its fuel consumption and the average fuel price.
• The logbook and odometer records, kept for five years after the end of the latest income year in which you rely on them.

That last rule runs long: a logbook kept in 2025–26 and relied on through 2029–30 has to be kept until 30 June 2035. For the car costs that need no paperwork at all, see what you can claim without receipts.

Can I keep an ATO logbook on my phone?

Yes. The ATO accepts electronic logbooks as well as printed ones from stationery suppliers, as long as the record holds everything in the table above.

The ATO’s own option is myDeductions, a free tool in the ATO app. Sole traders can record expenses, income and car trips in it and start a logbook, adding trips by GPS or point to point. Records can be uploaded to the ATO from 1 July, once per financial year, and can’t be changed in myDeductions afterwards.

Searches for an “ATO approved logbook app” usually turn up class rulings. The ATO has issued them for some electronic logbook products but states that a ruling is not an endorsement. Whatever you use, check the finished record against the ATO’s list, especially the odometer readings for each journey and for the period: a GPS distance alone is not the whole record.

…and where does Keel fit?

Keel: Invoice Maker & Receipts, by Ilura Technology OÜ, is an iPhone app for people who work for themselves. It keeps business mileage records next to your quotes, jobs, invoices, receipts and expenses, so a trip to a job sits with that job’s paperwork.

Keel is a record keeper, not a compliance tool. It does not produce an ATO-compliant logbook automatically, does not check your logbook against the ATO’s rules, and does not lodge anything with the ATO. For the logbook method you still record yourself: the car’s details, the dates of the 12-week period, odometer readings at the start and end of the period and of each journey, a specific reason for each business trip, your private kilometres, and odometer readings at the start and end of each later income year. Keep the running-cost receipts too.

Records stay on your iPhone: no account, no bank connection, no cloud sync, and the App Store privacy label reads “Data Not Collected”. Keel is free with no invoice limit; free invoices carry a small “Made with Keel” footer. Keel Lifetime is a one-time purchase ($249.99 USD; the App Store shows your local price) adding custom branding, a signature, premium templates and accountant-ready exports. Keel on the App Store. More Australian guides are on the Australia hub.

Frequently asked questions

How long do I need to keep an ATO logbook? Three time limits apply. The logbook period must be at least 12 continuous weeks. The logbook then stays valid for five years if your circumstances don’t change. And you must keep the logbook and odometer records for five years after the end of the latest income year in which you rely on them.

Can I use my old logbook for a new car? Yes, if you make a written nomination before you lodge your return, stating that you are replacing the original car with the new one and the date the nomination takes effect. If the new car comes with a change in how you use it for business, such as a new type of work, keep a fresh 12-week logbook instead.

Is there an ATO approved logbook app? There is no general list of approved apps. The ATO’s own free option is myDeductions in the ATO app, which can run a logbook for sole traders. The ATO has issued class rulings on some electronic logbook products but says they are not endorsements, so check any app against the ATO’s required details.

Is the logbook method better than cents per km? It depends on your driving and your car. Cents per kilometre pays 88 cents per km for 2025–26 and 91 cents for 2026–27, capped at 5,000 business km per car. The logbook has no cap, so it usually wins when you drive far more than 5,000 business kilometres or the car is expensive to run.

Can I start a logbook partway through the year? Yes. The 12 continuous weeks can fall anywhere in the income year, as long as they are representative of your travel for the whole year. If you started using the car for business less than 12 weeks before 30 June, keep the logbook going into the next income year until it covers 12 weeks.

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This article is general information, not tax advice. Consult a qualified Australian tax professional.