GST for sole-trader tradies: the $75k threshold, what to do, when to register

GST registration catches a lot of AU tradies mid-year when turnover suddenly crosses $75k and the ATO assumes you've registered. Here's the practical version — when you must register, what changes about quoting, and the mistakes to avoid.

When you must register

• Your GST turnover is $75,000+ in the current financial year, OR
• You expect your GST turnover to be $75,000+ in the next 12 months, OR
• You drive a ride-share / taxi vehicle (separate rule — $0 threshold),
• You want to claim GST credits on business expenses (voluntary registration)

GST turnover is gross revenue before any costs — not profit. If you're billing $7k/month consistently, you're at $84k annualised and must register, even if your take-home is much smaller.

What changes about your quotes

• Every quote must now show the GST-inclusive total clearly
• Your tax invoice must show the GST amount on a separate line
• You must include your ABN on every quote and invoice
• If the total is over $75, you must include the words 'tax invoice'
• You can now claim GST credits on fuel, tools, vehicle, insurance, subscriptions

The quarterly BAS cycle

Once registered, you pay BAS (Business Activity Statement) quarterly — due 28th of the month after each quarter ends (Oct, Jan, Apr, Jul). You pay GST you collected minus GST you paid on business purchases. Keep a separate 'GST account' and move 10% of every payment into it as you go — easier than scrambling at BAS time.

The common mistakes

1. Not registering on time. ATO backdates registration to when you first crossed $75k. Any quotes after that date had GST baked in whether you showed it or not — and you now owe that GST to the ATO.
2. Forgetting to claim GST credits. Most sole traders leave 3–5% on the table by not claiming credits on fuel, phone, subscription tools, or vehicle expenses.
3. Mixing GST funds into your main account. Easy to spend it. Move 10% of every incoming payment to a separate account the moment it lands.