You can only claim the full amount of the expense if the vehicle is solely used for business purposes.
If the vehicle is mixed use (personal and business) then you may claim up to 25% of the petrol as a business expense. Please note that IRD may ask you to substantiate the percentage claimed.
Petrol used for travel between work and home is not classified as business use and cannot be claimed.
Please enter the full cost of the receipt and select the percentage being claimed from the drop-down menu (defaulted to 25%). The system will automatically calculate the claimable amount for you.
NB: If you wish to claim more than 25% of all vehicle costs, you must keep a logbook for at least three months every three years. You will need to record the distance, date and reason for the trip in the logbook. You can use the difference between the odometer readings at the start and end of the three months to work out the percentage of vehicle expenses you can claim. See here for logbook template.