How GST works in Australia
Australia's Goods and Services Tax (GST) is a flat 10% added to most goods and services. If your business is registered for GST, you add 10% on top of your prices, collect it from your customers, and pass it on to the ATO when you lodge your BAS. The GST you pay on your own business purchases (your "input tax credits") is subtracted, so you only hand over the net.
Adding GST vs removing GST
There are two everyday sums tradies need:
- Adding GST — your price is GST-exclusive and you want the total. Multiply by 1.1. Example: a $500 job → $500 × 1.1 = $550, of which $50 is GST.
- Removing GST — you have a GST-inclusive total and want to know the GST portion. Divide the total by 11. Example: a $1,100 invoice → $1,100 ÷ 11 = $100 GST, leaving $1,000 ex-GST.
The "divide by 11" trick catches a lot of people out — because GST is 10% of the ex-GST price, it's only 1/11th (about 9.09%) of the GST-inclusive total, not 10% of it.
Do I need to register for GST?
As a sole trader, you must register for GST once your business turnover hits $75,000 in a 12-month period (current or expected). Under that, registering is optional. Some tradies register early so they can claim GST back on tools and a vehicle; others hold off to keep their quotes 10% cheaper to homeowners.
Quick reference
| You have… | You want… | Do this |
|---|---|---|
| Price before GST | Total with GST | × 1.1 |
| Total including GST | The GST portion | ÷ 11 |
| Total including GST | Price before GST | ÷ 1.1 |
What a valid tax invoice needs
If you're registered and the sale is over $82.50 (inc GST), your customer can ask for a tax invoice. For sales of $1,000 or more it must show: the words "Tax Invoice", your business name and ABN, the date, a description of what was supplied, the GST amount (or a note that the total includes GST), and the buyer's identity. Getting this right is what lets your business customers claim their own GST back.
GST calculator FAQ
How much is GST in Australia?
GST is 10% on most goods and services. A handful of items (basic food, some health and education) are GST-free.
How do I take GST off a price?
Divide the GST-inclusive total by 11 to get the GST amount, or by 1.1 to get the price before GST. On a $550 total, the GST is $50 and the ex-GST price is $500.
Is GST 10% of the total?
No — GST is 10% of the price before GST, which works out to 1/11th (≈9.09%) of the GST-inclusive total.
Do sole traders charge GST?
Only if you're registered for GST (required once turnover reaches $75,000). If you're not registered, you don't add GST and you don't issue tax invoices.
This calculator and guide are general information for Australian businesses, not tax advice. GST rules and thresholds can change — check the ATO GST pages or your accountant for your situation.