GST on $150
Both answers, because "GST on $150" means two different things depending on whether that figure already includes GST.
How much GST is on $150?
- If $150 is before GST: GST is $22.50 and the total becomes $172.50.
- If $150 already includes GST: the GST portion is $19.57 and the price before GST is $130.43.
- Working: $150.00 × 1.15 = $172.50 · $150.00 ÷ 23 × 3 = $19.57
$150, worked both ways
| Treating $150 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $22.50 | $150.00 | $172.50 |
| a total that includes GST | $19.57 | $130.43 | $150.00 |
| an Australian price at 10% | $15.00 | $150.00 | $165.00 |
The two NZ rows are the ones people mix up. Charging $22.50 of GST on an invoice whose total is meant to be $150 would leave you $2.93 short once Inland Revenue takes its cut — the GST inside $150 is only $19.57.
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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