GST on $1,200
Both answers, because "GST on $1,200" means two different things depending on whether that figure already includes GST.
How much GST is on $1,200?
- If $1,200 is before GST: GST is $180.00 and the total becomes $1,380.00.
- If $1,200 already includes GST: the GST portion is $156.52 and the price before GST is $1,043.48.
- Working: $1,200.00 × 1.15 = $1,380.00 · $1,200.00 ÷ 23 × 3 = $156.52
$1,200, worked both ways
| Treating $1,200 as… | GST | Ex GST | Inc GST |
|---|---|---|---|
| a price before GST | $180.00 | $1,200.00 | $1,380.00 |
| a total that includes GST | $156.52 | $1,043.48 | $1,200.00 |
| an Australian price at 10% | $120.00 | $1,200.00 | $1,320.00 |
The two NZ rows are the ones people mix up. Charging $180.00 of GST on an invoice whose total is meant to be $1,200 would leave you $23.48 short once Inland Revenue takes its cut — the GST inside $1,200 is only $156.52.
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
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