New Zealand GST calculator
Add 15% GST to a price, or work out how much GST is inside a GST-inclusive amount. Free, no signup, and accurate to the cent.
Add up a job
Quoting something with labour, materials and a callout? Enter each amount excluding GST and get the total to put on the invoice — GST is worked out once, on the subtotal.
How much GST do I owe IRD?
A quick estimate of your GST return: the GST collected on your sales, minus the GST paid on your business purchases, is what you pay (or get back).
What customers paid you in the period
Materials, tools, fuel — GST-able costs
Assumes everything's at the standard 15% rate and, if you file on the payments basis, that these are amounts actually paid in the period. Zero-rated or exempt items need taking out first.
How the maths works
New Zealand's GST rate is 15%. To add GST to a GST-exclusive price, multiply by 1.15 — so $100 excluding GST is $115 including GST.
To remove GST from a GST-inclusive price, divide by 1.15 — or use the shortcut IRD publishes: the GST inside a GST-inclusive amount is exactly three twenty-thirds (3/23) of it. On a $115 invoice, 115 × 3 ÷ 23 = $15 of GST. The common mistake is taking 15% of the inclusive amount ($17.25 on $115) — that overstates the GST, because the 15% was charged on the smaller, exclusive figure.
Worked examples
| Excluding GST | GST (15%) | Including GST |
|---|---|---|
| $100.00 | $15.00 | $115.00 |
| $250.00 | $37.50 | $287.50 |
| $1,000.00 | $150.00 | $1,150.00 |
| $4,347.83 | $652.17 | $5,000.00 |
When do you charge GST?
Only GST-registered businesses charge GST. Registration is compulsory once your turnover passes $60,000 in any 12-month period (or you expect it to), and voluntary below that. If you're not registered, you don't add GST to your invoices at all — and you can't claim it back on expenses either. Our guide Do I need to register for GST? walks through the threshold and the trade-offs.
GST return due dates
GST returns and payment are due on the 28th of the month after your taxable period ends, with two exceptions IRD builds in every year: the period ending 30 November is due 15 January (summer break), and the period ending 31 March is due 7 May (end of the tax year). When the 28th lands on a weekend or public holiday, the due date moves to the next working day. Which period-ends apply to you depends on your filing frequency — two-monthly filers use every second row, six-monthly filers commonly the March and September ones.
| Taxable period ending | Return & payment due |
|---|---|
| 31 July 2026 | 28 August 2026 |
| 31 August 2026 | 28 September 2026 |
| 30 September 2026 | 28 October 2026 |
| 31 October 2026 | 30 November 2026 (28th is a Saturday) |
| 30 November 2026 | 15 January 2027 (summer-break exception) |
| 31 December 2026 | 28 January 2027 |
| 31 January 2027 | 1 March 2027 (28 Feb is a Sunday) |
| 28 February 2027 | 29 March 2027 (28th is a Sunday) |
| 31 March 2027 | 7 May 2027 (end-of-tax-year exception) |
| 30 April 2027 | 28 May 2027 |
| 31 May 2027 | 28 June 2027 |
| 30 June 2027 | 28 July 2027 |
File and pay through myIR. Dates follow IRD's standard rules — confirm your own dates in myIR, especially if you have a non-standard balance date.
Sick of doing this by hand?
PayMint works out the GST on every invoice automatically — set your GST registration status once, and every invoice, quote and GST report gets it right. Your customer pays by card and the money lands in your own bank account. It costs 1% per paid invoice (plus Stripe's card fee), with no monthly cost.
Try PayMint freeThis calculator uses the standard 15% GST rate. It's a convenience tool, not tax advice — for your specific situation, talk to an accountant or check ird.govt.nz.