GST on $80
Both answers, because "GST on $80" means two different things depending on whether that figure already includes GST.
How much GST is on $80?
- If $80 is before GST: GST is $12.00 and the total becomes $92.00.
- If $80 already includes GST: the GST portion is $10.43 and the price before GST is $69.57.
- Working: $80.00 × 1.15 = $92.00 · $80.00 ÷ 23 × 3 = $10.43
$80, worked both ways
| Treating $80 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $12.00 | $80.00 | $92.00 |
| a total that includes GST | $10.43 | $69.57 | $80.00 |
| an Australian price at 10% | $8.00 | $80.00 | $88.00 |
The two NZ rows are the ones people mix up. Charging $12.00 of GST on an invoice whose total is meant to be $80 would leave you $1.57 short once Inland Revenue takes its cut — the GST inside $80 is only $10.43.
The two calculations
Adding GST to a GST-exclusive price.
Finding the GST already inside a total.
Stripping GST out to get the ex-GST price.
Taking 15% of a GST-inclusive figure is the common error — it overstates the GST every time. Full guide, with the registration rules and the $60,000 threshold →
Do the next bit too
The number is the easy part. These take it the rest of the way.
Make the invoice
Turn this figure into a compliant GST tax invoice with your logo and download the PDF. The amount carries across automatically.
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Hnry takes your income, works out the GST, ACC and income tax, pays them and files the returns. Built for NZ sole traders.
See Hnry →GST on other amounts
The rest of the toolkit
Ten free tools that talk to each other — send hours or an accepted quote straight into an invoice without retyping a thing. No signup on any of them.