How to Calculate GST in Australia

The 10% Goods and Services Tax — adding it, removing it, and using it correctly on invoices.

Australia has charged a 10% Goods and Services Tax on most goods and services since July 2000. If you run a business that's registered for GST, issue invoices, do bookkeeping, or even just want to check a receipt, you need to know two things: how to add GST to a tax-exclusive price and how to remove GST from a tax-inclusive price. The maths is straightforward but easy to get backwards.

Skip the maths: drop your figure into the GST Calculator Australia and it will instantly add or remove 10% GST — and switch presets for New Zealand (15%), the United Kingdom (20%), or any custom rate.

The current GST rate

Australia's GST rate is 10%. It hasn't changed since the system started on 1 July 2000. New Zealand uses 15%, most of the European Union uses 19–25%, and the United Kingdom uses 20% (called VAT). Always confirm the rate for the country you're invoicing — international clients usually want a tax-exclusive price plus the local tax line.

Adding 10% GST to a price

If your tax-exclusive (net) price is P, the GST-inclusive (gross) price is:

Gross = P × 1.10

Examples:

$100 net → $100 × 1.10 = $110 gross ($10 GST)
$45 net → $45 × 1.10 = $49.50 gross ($4.50 GST)
$2,200 net → $2,200 × 1.10 = $2,420 gross ($220 GST)

Removing GST from a price (the divide-by-11 trick)

This is where most people slip up. To find the GST component hidden inside a tax-inclusive price, you don't multiply by 10% — you divide by 11. To find the GST-exclusive (net) amount, divide by 1.10.

GST component = Gross ÷ 11
Net = Gross ÷ 1.10

Examples:

$110 gross → GST = $110 ÷ 11 = $10; Net = $110 ÷ 1.10 = $100
$1,650 gross → GST = $1,650 ÷ 11 = $150; Net = $1,500
$77 gross → GST = $77 ÷ 11 = $7; Net = $70

Common mistakes

Subtracting 10% from a gross price. $110 minus 10% is $99, not $100. Always divide by 1.10 instead.
Forgetting GST-free items. Most basic food, most education, and most health services are GST-free. Don't apply 10% to a fresh-fruit invoice line.
Mixing inclusive and exclusive prices. Decide once for the whole quote — never quote one line ex-GST and another inc-GST.
Rounding too early. If you're invoicing many lines, round only the final totals, not each line.

When you must register for GST

You must register for GST if your business has an annual GST turnover of $75,000 or more (or $150,000+ for non-profits). Below that, registration is optional but lets you claim GST credits on inputs. Once registered, you must add GST to taxable supplies, issue tax invoices, and remit GST to the ATO each month or quarter.

Official sources

For the authoritative rules — including GST-free supplies, input tax credits, the simplified GST method for small business, and the wine equalisation tax — see the ATO's GST guidance: ato.gov.au — GST.

Last updated: May 2026. This article is a general guide only and is not financial, tax, legal, or professional advice.

Try it now

Open the GST Calculator Australia and drop in any figure to see the GST split instantly. For salary scenarios that interact with GST (sole-trader pay-as-you-go), pair it with the Pay Calculator Australia.