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Working out your GST

Find out how to calculate goods and services tax (GST) for your GST return.

Before you can work out your GST total, you need to calculate your sales and income and your purchases and expenses. You may also need to make some GST adjustments. We'll step you through the process.

Calculate your sales and income

Follow these steps to calculate your sales and income. You need to enter the figures you get from each of these calculations into your GST return. If you file your GST return through myIR many of the calculations will be made for you automatically.

  1. If you use the payments basis
    Add up all the payments you received for taxable supplies during the taxable period. Enter this figure in box 5 of your GST return.
    If you use the invoice or hybrid basis
    Add up all the payments received and invoices issued for taxable supplies you made in the taxable period. Enter this figure in box 5 of your return.
  2. Add up the total of your zero-rated supplies for the taxable period. Enter this figure in box 6 of your return.
  3. Subtract the total of your zero-rated supplies from your total sales and income, and enter this figure in box 7 of your return.
  4. Multiply box 7 by 3, then divide by 23 and enter this figure in box 8 of your return.
  5. Add up any adjustments on sales and income from your GST adjustments calculations sheet (IR372). Enter this figure in box 9 on your return.
  6. Then add the calculations from box 8 and box 9 and enter this figure in box 10 on your return. This is the total amount of GST collected on sales and income.
What do we mean when we say zero-rated supplies?

Certain taxable supplies are taxed at the rate of 0% rather than at the standard rate of 15%. You must include all zero-rated supplies on your GST return along with your total taxable supplies.

Find out more about zero-rated supplies

Calculate your purchases and expenses

Follow these steps to calculate your purchases and expenses that include GST. You need to enter the figures from each of these calculations into your GST return.

  1. If you use the invoice basis
    Add up all the payments made and invoices received for taxable supplies within the taxable period. Note: you must hold the necessary tax invoices and GST records. Enter this figure in box 11 of your GST return.
    If you use the payments or hybrid basis
    Add up all the payments you made for purchases and expenses that include GST during the taxable period. Note: you must hold the necessary tax invoices and GST records. Enter this figure in box 11 of your GST return.
  2. Our online eGST return service will automatically multiply box 11 by 3, then divide by 23 and enter the figure in box 12 on your return.
  3. Add up the total of any credit adjustments on purchases and expenses from box 13 on your GST adjustments calculation sheet (IR372). Enter this figure in box 13 on your GST return.
  4. Our online eGST return service will add box 12 and box 13. This figure will automatically be entered in box 14 on your GST return. This is the total amount of GST paid on purchases and expenses.

GST adjustments

If you use a business asset for private use, you need to make a GST adjustment in your GST return to allow for the private use of the asset.

Find out more about GST adjustments

Calculate your GST total

Our online eGST return service will automatically:

  • subtract the total GST you've paid on your purchases and expenses (box 14 on your return) from the total GST you've collected from your sales and income (box 10 on your return)
  • enter the figure in box 15 on your return.

If you've:

  • paid out more GST than you've collected, you receive a refund
  • collected more GST than you've paid, you need to pay the balance to us by the due date.

Next steps

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