Vehicle Logbook Business Use Calculator
Calculate your business use percentage from a 12-week logbook to work out deductible car expenses under the ATO logbook method.
Your results
Calculation breakdown
- Business use %
- Business use % = business km / total km
- Deduction
- Deduction = total running costs × business use %
Worked example
A logbook showing 8,000 business km out of 15,000 total km gives a 53.3% business use, deducting about $4,533 from $8,500 running costs.
Assumptions
- Requires a valid continuous 12-week logbook.
- Logbook remains valid up to five years unless usage patterns change significantly.
How this calculator works
The ATO logbook method lets you claim the business-use percentage of your total car running costs, based on a valid 12-week logbook. Enter your logbook's business kilometres and total kilometres, plus your total annual running costs, to estimate your deductible amount.
Rates sourced from the Australian Taxation Office for the 2026–27 financial year. Last reviewed 01/07/2026.
Frequently asked questions
How long must a logbook be kept?
The ATO requires a continuous logbook for at least 12 weeks, which is then valid for up to five years unless your business use pattern changes significantly.
What counts as total running costs?
Include fuel, insurance, registration, servicing, interest on a car loan and decline in value, as these are the eligible expense categories under the logbook method.
What if I don't have a logbook?
Without a valid logbook you must use the cents per kilometre method instead, capped at 5,000 business kilometres per car per year.
Rates and thresholds are configured for the 2026–27 Australian financial year and should be reviewed when government settings change.