GST and BAS Basics for Newly-ABN Tradies

Somewhere around your first really good year on the tools, a number starts creeping up on you: $75,000. Cross it, and your ABN stops being a simple “invoice and get paid” setup and starts involving GST, tax invoices, and a whole new lodgement on your calendar. Here’s what actually changes.

The short version (TL;DR)

• You must register for GST once your turnover reaches, or is reasonably expected to reach, $75,000 in any rolling 12-month period — not just measured at 30 June.
• You have 21 days from becoming aware you’ll cross the threshold to actually register.
• Once registered, you must charge GST on your invoices, issue proper tax invoices, and lodge a BAS (Business Activity Statement) regularly — even in a quarter with no sales.
• Your GST turnover is not the same as profit — it’s based on income, and high expenses don’t reduce it.
• Registering late isn’t just admin — the ATO can backdate your registration and require you to pay GST on past sales, plus interest and penalties.

Why the $75,000 figure catches tradies out

A lot of subbies mentally track the threshold against their bank balance or their profit, when it’s actually based on turnover (total invoiced income) — which climbs a lot faster than take-home profit once you’re covering vehicle costs, materials, and tool finance. Because it’s assessed on a rolling 12-month basis rather than just at end of financial year, you can genuinely cross the threshold mid-year without realising it until your bookkeeping catches up.

What actually changes once you’re registered

• You add GST to your invoices — generally 10% on top of your price, which your client pays (they can usually claim it back if they’re GST-registered themselves; if they’re a private homeowner, it’s a real cost to them).
• You issue proper tax invoices, not just a basic invoice — there are specific requirements for what a tax invoice needs to include.
• You lodge a BAS, typically quarterly, reporting the GST you’ve collected and the GST you’ve paid on business expenses (materials, tools, vehicle costs) — the difference is what you pay to, or claim back from, the ATO.
• You need to lodge even with no sales in a period — a “nil” BAS is still a required lodgement, not something you can skip because there’s nothing to report.

The upside: claiming GST credits

It’s not purely a cost — once registered, you can generally claim back the GST you’ve paid on legitimate business expenses (tools, materials, ute running costs, insurance) as GST credits, which offset what you owe on the GST you’ve collected. For tradies with genuinely significant tool and vehicle costs, this can meaningfully soften the impact of having to charge GST in the first place.

What happens if you register late

This is the part that actually costs money: if the ATO determines you should have registered earlier, they can backdate your registration to when you crossed the threshold — meaning you may owe GST on sales you already made and already spent the money from, plus interest and potential penalties. Keeping an eye on your rolling 12-month turnover, rather than waiting for a tax return to reveal the problem, is the practical way to avoid this.

Frequently asked questions

Do I have to register for GST as soon as I get my ABN?
No — registration is only required once your turnover reaches, or you reasonably expect it to reach, $75,000 in a rolling 12-month period. Below that, GST registration is optional.

Is the $75,000 threshold based on profit or income?
It’s based on turnover (income), not profit — your business expenses don’t reduce your GST turnover for threshold purposes, which is exactly why tradies with high material and vehicle costs can cross it faster than expected.

What if I have a quiet quarter with barely any invoices?
You still need to lodge your BAS once registered, even if it’s a “nil” or very low activity statement — the obligation is to lodge on schedule, not just when there’s meaningful activity to report.

Can I voluntarily register before I hit $75,000?
Yes, and some tradies do this specifically to claim GST credits on big upfront purchases (a ute, a major tool investment) — worth discussing with an accountant if you’re planning a large purchase early in your business.

This guide is general information only — not tax advice. GST and BAS rules and thresholds can change; confirm your current obligations with the ATO or a registered tax agent before making decisions.

Sources:
Stripe — The Australia GST Threshold Explained for Growing Businesses
ATO — GST registration and turnover requirements (confirm current thresholds directly at ato.gov.au)