Vehicle Logbook Calculator NZ
This calculator works out the business use percentage of a vehicle from your logbook figures and the portion of your running costs you can claim as a tax deduction. If you use a vehicle for both business and private travel, you can only deduct the business share of its running costs, and the standard way to establish that share is to keep a logbook. Inland Revenue accepts a representative logbook kept for at least 90 consecutive days, which then sets your business use percentage for up to three years, provided your use does not change much. That percentage is applied to all your vehicle running costs, fuel, maintenance, insurance, registration, depreciation and so on, to find the deductible amount. This tool does the calculation. You enter the business kilometres and the total kilometres from your logbook, and your total annual running costs, and the calculator returns the business use percentage, the deductible portion of your costs, the private portion, and the running costs for reference. The results update as you type, so you can see how more business travel increases your claim. Use it to work out a vehicle expense deduction for a business or self-employment, to check a logbook result, or to estimate the tax benefit of business travel. The business use percentage is simply your business kilometres divided by your total kilometres. Keeping an accurate logbook is the key, since without one your deduction is limited. A practical note: the logbook method suits people with significant vehicle running costs, while those with light vehicle use may find the kilometre-rate method, claiming a set rate per business kilometre, simpler. This calculator covers the logbook method, the most common approach for claiming actual costs.
Business use % = business km / total km. Deduction = running costs x business %. A logbook kept 90 days sets the percentage for up to 3 years. Keep accurate records.
How it works
The business use percentage is the business kilometres divided by the total kilometres travelled. That percentage is then applied to your total vehicle running costs to find the deductible business portion, with the remainder being the non-deductible private portion. A representative 90-day logbook can set this percentage for up to three years.
Worked example
With 8,000 business kilometres out of 15,000 total, the business use percentage is 8,000 divided by 15,000, about 53.33 percent. Applied to $6,000 of annual running costs, the deductible business portion is 53.33 percent of $6,000, which is $3,200, leaving $2,800 as the private, non-deductible portion.
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