GST registration trips up a lot of tradies going out on their own. The good news is the rule is simple once you strip away the jargon: it all comes down to one number — $75,000 — and one thing most people get wrong about what that number actually measures.
The $75,000 rule — and the bit people get wrong
The threshold is $75,000 in turnover, and turnover means your total business income before you take out any expenses. This is the single most common mistake: tradies think it is profit. It is not. If you invoice $80,000 and spend $30,000 on materials, your turnover is $80,000 — you are over the threshold, even though you only "made" $50,000.
The test is also rolling. You look at both the last 12 months and the next 12 months. If at any point you can reasonably see you will cross $75,000, that is when the clock starts.
When you must register
- Your turnover has reached $75,000 over the past 12 months, or
- You expect to reach $75,000 in the next 12 months (e.g. you have just landed a run of big jobs).
- Once either is true, you have 21 days to register.
Free GST Calculator
Work out the GST to add to a price, or back it out of a total, in seconds — handy the moment you register and start putting 10% on your quotes and invoices. No signup.
Open the free toolShould you register early (before $75k)?
Below the threshold it is your call. Registering voluntarily has trade-offs:
Reasons some tradies register early
- You can claim GST credits on tools, materials, fuel and vehicle costs — useful if you buy a lot of gear.
- You look established to commercial clients and other GST-registered businesses.
- You avoid a price jump later, since you are charging GST from the start.
Reasons to hold off
- More admin — you have to lodge a BAS and track GST.
- If most of your customers are homeowners who cannot claim GST back, adding 10% makes you 10% dearer to them.
What changes once you are registered
- You add 10% GST to your prices.
- You issue proper tax invoices (with your ABN and the GST shown).
- You lodge a Business Activity Statement (usually quarterly) and pay the ATO the GST you collected, minus the GST you paid on business purchases.
Frequently asked questions
You must register for GST once your business turnover reaches $75,000 or more in a 12-month period — that is total income before expenses, not profit. The test looks at both the current and projected 12 months, so if you can see you are on track to hit $75,000, you need to register.
No — registration is optional below the threshold. Some tradies register voluntarily anyway so they can claim GST credits on tools, materials and vehicle costs, but for many under the threshold it is simpler to stay unregistered. It is a case-by-case call.
You add 10% GST to your prices, report it to the ATO on a Business Activity Statement (usually quarterly), and pay the GST you have collected minus the GST you have paid on business purchases (your input tax credits). You will also need to issue proper tax invoices.
You have 21 days to register for GST once your turnover reaches the $75,000 threshold or you become aware you will exceed it. Leaving it late can mean you owe GST on sales you did not charge it on, so keep an eye on your running 12-month total.
Let the admin sort itself out
Admin Substitute puts the right GST on every quote and invoice, keeps your records tidy for BAS time, and chases overdue payments — so registering for GST does not mean drowning in paperwork.
30-day money-back guarantee · No lock-in contracts · 90% cheaper than hiring an admin