Calculating your GST

GST Dates

AUG 28

Your GST return and payment is due for the taxable period ending 31 July.
SEP 28

Your GST return and payment is due for the taxable period ending 31 August.
OCT 28

Your GST return and payment are due for the taxable period ending 30 September. (This is an extension of the usual 28 October due date.)

All GST dates

Most people file their GST return in myIR which does the calculations for you. If you file a paper return the form tells you what calculations to make.

Regardless of how you file you need to work out your total:

sales and income
zero-rated supplies
debit adjustments
purchases and expenses
credit adjustments

Sales and income

The way you work out your total sales and income depends on the accounting basis you use.

You use the invoice or hybrid basis	You use the payments basis
Add up all the invoices you issued for your taxable supplies during the taxable period. Then, add any payments received for taxable supplies during the taxable period that you have not already accounted for.	Add up all the payments you received for your taxable supplies during the taxable period.

Zero-rated supplies

Add up all your zero-rated supplies for the taxable period.

Zero-rated supplies

Debit adjustments

Add up all your debit adjustments for the taxable period.

GST debit adjustments

Purchases and expenses

The way you work out your total purchases and expenses depends on the accounting basis you use.

You use the invoice or hybrid basis	You use the payments basis
Add up all the invoices you've received for purchases and expenses that include GST during the taxable period. Then, add any payments made for purchases and expenses that you have not already accounted for. You must have tax invoices for these purchases and expenses.	Add up all the payments you made for purchases and expenses that include GST during the taxable period. You must have tax invoices for these purchases and expenses.

You use the invoice or hybrid basis

You use the payments basis

Add up all the invoices you've received for purchases and expenses that include GST during the taxable period. Then, add any payments made for purchases and expenses that you have not already accounted for.

You must have tax invoices for these purchases and expenses.

Add up all the payments you made for purchases and expenses that include GST during the taxable period.

You must have tax invoices for these purchases and expenses.

You can only claim part of the GST charged on a purchase that will not be exclusively used in your business.

GST adjustments for business or private use