Tax rule NZ
Business use: the vehicle logbook
The logbook Inland Revenue accepts for the business share of a vehicle, and the years Bilbx's Tax Lab applies it for.
The record for a vehicle
90-day logbook, for 3 years
Checked against Inland Revenue's own pages on . This is the figure Bilbx uses.
The rule
You can work out the business use of your vehicle by keeping a logbook for at least 90 consecutive days.
What Inland Revenue says
“You can work out the business use of your vehicle by keeping a logbook for at least 90 consecutive days.”
The calculation can be used for up to 3 years if the proportion of business use does not change by more than 20%; after 3 years, you keep a logbook for another 90 days.
What Inland Revenue says
“Your calculation can be used for up to 3 years if the proportion of business use doesn't change by more than 20%.”
“After 3 years you will need to keep a logbook for another 90 days.”
How Bilbx applies it
- Tax Lab, part of Bilbx Premium, applies a category's business-use share for the tax years its record covers: 90-day logbook, for 3 years; usage diary, for its own year; floor area, until you change it.
- When a record no longer covers the year, Settings asks for a new one.
Worked examples
Bilbx's own tests run these exact cases against the website and the app.
| Record | Made in the tax year starting | Read in | Tax Lab |
|---|---|---|---|
| 90-day logbook | 2024 | 2026 | Applies the share |
| 90-day logbook | 2024 | 2027 | Asks for a new record |
| Usage diary | 2025 | 2026 | Asks for a new record |
| Floor area | 2020 | 2030 | Applies the share |
Sources
Spotted something that doesn't match Inland Revenue's guidance?
Every sentence in the rule is checked against Inland Revenue's own guidance, quoted beneath it and linked above. Last checked . Rules version 60f9162250af. Terms.
More for New Zealand: every tax rule Bilbx applies and guides on receipts and tax records.