GST on $75
Both answers, because "GST on $75" means two different things depending on whether that figure already includes GST.
How much GST is on $75?
- If $75 is before GST: GST is $11.25 and the total becomes $86.25.
- If $75 already includes GST: the GST portion is $9.78 and the price before GST is $65.22.
- Working: $75.00 × 1.15 = $86.25 · $75.00 ÷ 23 × 3 = $9.78
$75, worked both ways
| Treating $75 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $11.25 | $75.00 | $86.25 |
| a total that includes GST | $9.78 | $65.22 | $75.00 |
| an Australian price at 10% | $7.50 | $75.00 | $82.50 |
The two NZ rows are the ones people mix up. Charging $11.25 of GST on an invoice whose total is meant to be $75 would leave you $1.47 short once Inland Revenue takes its cut — the GST inside $75 is only $9.78.
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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The rest of the toolkit
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