GST on $800
Both answers, because "GST on $800" means two different things depending on whether that figure already includes GST.
How much GST is on $800?
- If $800 is before GST: GST is $120.00 and the total becomes $920.00.
- If $800 already includes GST: the GST portion is $104.35 and the price before GST is $695.65.
- Working: $800.00 × 1.15 = $920.00 · $800.00 ÷ 23 × 3 = $104.35
$800, worked both ways
| Treating $800 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $120.00 | $800.00 | $920.00 |
| a total that includes GST | $104.35 | $695.65 | $800.00 |
| an Australian price at 10% | $80.00 | $800.00 | $880.00 |
The two NZ rows are the ones people mix up. Charging $120.00 of GST on an invoice whose total is meant to be $800 would leave you $15.65 short once Inland Revenue takes its cut — the GST inside $800 is only $104.35.
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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