Enter an amount and choose whether it already includes GST. The calculator shows the GST-exclusive amount, the GST and the GST-inclusive amount, rounded to the cent.
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The rate is 10%. GST is a 10% tax on most goods, services and other items sold or consumed in Australia.
| GST-exclusive | GST | GST-inclusive | |
|---|---|---|---|
| Quote $1,000 + GST | $1,000.00 | $1,000.00 × 10% = $100.00 | $1,100.00 |
| Receipt for $100 including GST | $100.00 − $9.09 = $90.91 | $100 ÷ 11 = $9.0909… → $9.09 | $100.00 |
Rounding: for an invoice with one taxable sale, the ATO says to round GST to the nearest cent, rounding half a cent up. This calculator does that. Invoices with several taxable sales have their own rounding rules (see the ATO tax invoices page), so a line-by-line total can differ by a cent or two.
If you're registered for GST, or required to be, the goods and services you sell in Australia are taxable (GST is in the price) unless they're GST-free or input-taxed.
You must register for GST:
Once you're required to register, you have 21 days to do it. Otherwise registering is optional.
Not every sale includes GST. Some things are GST-free, including most basic food, some education courses and some medical, health and care services, as well as exports and others on the ATO list. Don't use this calculator to add GST to a GST-free sale.
The A$82.50 tax invoice threshold. If a customer asks for a tax invoice, you must give them one within 28 days unless the sale is A$82.50 (including GST) or less. Buyers need a tax invoice to claim a GST credit for a purchase that cost more than A$82.50 (including GST).
Sources (checked 17 Oct 2026): ATO Goods and services tax (GST) (the 10% rate); When you can claim a GST credit (divide by 11; the A$82.50 rule for claiming credits); Tax invoices (28 days, A$82.50, rounding); Taxable sales; Registering for GST (A$75,000 threshold, taxi and ride-sourcing, 21 days); GST-free sales.
General information, not tax advice. It doesn't take your circumstances into account. Check with the ATO or a registered tax agent before relying on it.