GST calculator

Add GST to a price at New Zealand's 15 per cent, or work out how much GST is already sitting inside a GST-inclusive total. Free, no sign-up, and it does the awkward direction correctly.

NZ$

New Zealand · GST at 15 per cent

Price excluding GST
NZ$150.00
GST, at 15 per cent
NZ$22.50
Total including GST
NZ$172.50

The mistake worth avoiding

Removing GST is not the same operation as adding it. If a client pays you NZ$172.50 including GST, the GST is NZ$22.50 - the total multiplied by 3 and divided by 23. Taking 15 per cent off NZ$172.50 gives NZ$25.88, which is a different number and the wrong one. It is an easy slip to make when you do your GST return, and it misstates what you actually collected.

Common questions

How do I add GST to a price in New Zealand?
Multiply the GST-exclusive price by 1.15. A service priced at NZ$150 excluding GST becomes NZ$172.50 including GST, of which NZ$22.50 is GST. Inland Revenue's own example: NZ$100 plus GST is NZ$115.
How do I work out the GST inside a GST-inclusive price?
Multiply the GST-inclusive total by 3 and divide by 23: Inland Revenue puts the GST inside a GST-inclusive price at 3/23 of it. On a NZ$172.50 GST-inclusive price the GST is NZ$22.50. Taking 15 per cent off the total instead gives NZ$25.88, which is wrong and over-states the GST in the price. This is the single most common GST arithmetic error.
Do I have to charge GST as a sole trader?
Only if you are registered for GST. Inland Revenue says you must register if your turnover was at least NZ$60,000 in the last 12 months, or you expect it to be at least NZ$60,000 in the next 12 months, and you can choose to register below that. If you are not registered you do not charge GST and you cannot claim GST on your expenses.
Should I show my prices including or excluding GST?
Inland Revenue describes both ways of handling it: adding GST to your prices (NZ$100 plus GST, NZ$115 in total), or taking GST off the price you receive (NZ$100 including GST holds NZ$13.04 of GST). Whichever you choose, say which it is, so a client knows what they will pay.

General information only, current at the time of writing. It is not tax advice and does not account for your circumstances. For anything that matters, check with your accountant or Inland Revenue.

Stop doing this by hand on every invoice

BookAndGo issues invoices with your NZBN and the GST worked out for you at New Zealand's 15 per cent, and sends a receipt when you mark them paid. If you are not registered for GST, it simply leaves GST off.

  • Invoices numbered in sequence, with your NZBN and business details
  • GST shown as its own line, or left off entirely if you are not registered
  • Issued automatically when an appointment is completed
  • Receipts sent when you mark an invoice paid, without you chasing
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