Do I need to register for GST?

The threshold

You must register for GST when your GST turnover reaches $75,000 — and 'reaches' is forward-looking: you register when your current turnover over the last 11 months plus the current month hits it, or when you reasonably expect the next 12 months to. It's turnover (sales), not profit, and the clock doesn't reset each financial year.

Two groups register from the first dollar regardless of turnover: taxi, limousine and ride-share drivers, and anyone who wants to claim fuel tax credits.

What changes when you register

You add 10% GST to your taxable sales, and that 10% is never your money — you're collecting it for the ATO. In exchange you claim back the GST inside your business purchases. You lodge a Business Activity Statement, usually quarterly, that nets the two off. Your invoices become tax invoices with the fields that entails.

Under the threshold: registering by choice

Below $75,000, registration is optional, and it's a genuine trade-off. Registering lets you claim GST credits on your costs and can read as 'established' to business customers — but it adds 10% to your prices (which matters if your customers are the public and can't claim it back), and it commits you to BAS lodgement, usually for at least 12 months.

There's no universal right answer — it depends on who your customers are and how GST-heavy your costs run. It's a good question to put to a registered tax or BAS agent with your actual numbers in hand.

If you cross the line

You have 21 days to register once you're required to. Leave it late and the ATO can treat your prices as having included GST you never collected — one-eleventh of every sale, out of your pocket, plus possible penalties. If you're anywhere near $75,000 and climbing, watch the rolling number monthly rather than discovering it at tax time.