Vehicle expense claim calculator
Understand what you can claim
If you use your own car for work, you may be able to claim a portion of your vehicle costs at tax time. The IRD lets you claim the business portion of your vehicle costs against your taxable income, but between tiered kilometre rates, logbook rules, and GST catches, working out exactly what you’re owed isn’t always straightforward.
This calculator takes a few basic inputs and gives you an estimate that reflects the current IRD rates and thresholds. Less guesswork, more confidence when you file.
How your claim is calculated
Understanding the logic behind the numbers will help you enter the right inputs and trust the result you get.
Total km vs business km.
The calculator asks for both. Your total annual kilometres includes all driving, personal and business combined. Your business kilometres is just the work portion. The tool uses these two figures to calculate your business-use percentage, which determines how much of the total claim you can keep.
The two-tier rate system.
The IRD doesn't apply a single flat rate to all your kilometres. Instead, it uses two tiers. The higher Tier 1 rate covers the first 14,000 km of your total driving (business and personal combined), while the lower Tier 2 rate applies to everything above that. The calculator then applies your business-use percentage to both tiers to work out the claimable amount. A common mistake is applying the Tier 1 rate to the first 14,000 km of business travel only, which would overstate the portion calculated at the higher rate. Select your vehicle type in the dropdown (petrol, diesel, hybrid, or electric) and the correct rates are applied automatically.
The logbook rule.
If you've maintained a valid 90-day logbook, toggle Yes and the calculator will use your actual business-use percentage. If you haven't kept one, toggle No. The IRD generally limits claims to a maximum of 25% without a valid logbook, even if you drove more for work. As the example below shows, that difference can be significant.
The GST catch.
When using the IRD's per-kilometre method, GST is already factored into the rate. You can't separately claim it in your GST return. The calculator reflects this so you won't accidentally double up.
See the difference a logbook makes
A tradesperson drives 45,000 km in a year using a petrol vehicle, with 35,000 km for work. With a valid logbook, their business-use percentage is roughly 78%.
With mortgage interest included
| First 14,000 km at Tier 1 ($1.17) | Apportioned for business use = $12,740 |
| Remaining 31,000 km at Tier 2 ($0.37) | Apportioned for business use = $8,921 |
| Total Vehicle Claim | $21,661 |
One more thing to keep in mind
The IRD’s kilometre rates change periodically, and different vehicle types carry different rates. This calculator uses the latest published rates, but it’s worth checking the IRD website if you’re filing for a previous tax year.
Want the full picture?
Our Ultimate guide to claiming work-related vehicle expenses covers how these rules apply across different business structures and vehicle types.
Tax time putting pressure on cash flow?
A solid claim reduces your tax bill, but tax season can still hit at the worst time for cash flow. If you need to bridge a gap, we can help with fast, flexible funding built for small businesses.
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FAQs
Common questions answered
Generally, no. You typically only need to maintain one for a continuous 90-day period. That logbook then establishes your business-use percentage for up to three years, provided your driving habits stay broadly the same.
Driving between job sites, heading to client meetings, and picking up supplies all count. Your daily commute to a regular place of work generally doesn’t, even if you’re self-employed.
- If your employer already reimburses you at or above the IRD rates, there’s generally nothing further to claim. If they reimburse at a lower rate, you may be able to claim the shortfall. This is one where a conversation with your tax agent is worth having.
