GST on $600
Both answers, because "GST on $600" means two different things depending on whether that figure already includes GST.
How much GST is on $600?
- If $600 is before GST: GST is $90.00 and the total becomes $690.00.
- If $600 already includes GST: the GST portion is $78.26 and the price before GST is $521.74.
- Working: $600.00 × 1.15 = $690.00 · $600.00 ÷ 23 × 3 = $78.26
$600, worked both ways
| Treating $600 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $90.00 | $600.00 | $690.00 |
| a total that includes GST | $78.26 | $521.74 | $600.00 |
| an Australian price at 10% | $60.00 | $600.00 | $660.00 |
The two NZ rows are the ones people mix up. Charging $90.00 of GST on an invoice whose total is meant to be $600 would leave you $11.74 short once Inland Revenue takes its cut — the GST inside $600 is only $78.26.
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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See Hnry →GST on other amounts
The rest of the toolkit
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