GST on $25
Both answers, because "GST on $25" means two different things depending on whether that figure already includes GST.
How much GST is on $25?
- If $25 is before GST: GST is $3.75 and the total becomes $28.75.
- If $25 already includes GST: the GST portion is $3.26 and the price before GST is $21.74.
- Working: $25.00 × 1.15 = $28.75 · $25.00 ÷ 23 × 3 = $3.26
$25, worked both ways
| Treating $25 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $3.75 | $25.00 | $28.75 |
| a total that includes GST | $3.26 | $21.74 | $25.00 |
| an Australian price at 10% | $2.50 | $25.00 | $27.50 |
The two NZ rows are the ones people mix up. Charging $3.75 of GST on an invoice whose total is meant to be $25 would leave you $0.49 short once Inland Revenue takes its cut — the GST inside $25 is only $3.26.
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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