Do I need to register for GST?

Only if your projected next-12-month GST turnover is $75,000 or more. Below that threshold, registration is optional. The ATO requires you to register within 21 days of becoming aware that you'll exceed the threshold — once you're confident a contract or trajectory will tip you over, the clock starts.

Often yes, if you spend a meaningful amount on materials at GST-inclusive prices (Reece, Bunnings Trade, Mitre 10) and most of your customers are businesses. Registering means: (a) you charge 10% GST on every taxable supply (mostly a wash for B2B customers who claim it back); (b) you can claim back GST on every business purchase. The break-even point is usually around $5k–$10k of annual materials spend, but the BAS-paperwork cost is the other side of the ledger.

You can cancel your GST registration if your projected next-12-month turnover drops below $75k. Submit a cancellation via the ATO's Business Portal. You'll need to lodge a final BAS for the period up to the cancellation date and may owe GST on remaining inventory / business assets at fair-market value. Talk to your accountant before cancelling — once you're out, re-registering involves the 21-day clock again.

BAS = Business Activity Statement. It's the form where you report GST collected (output GST) minus GST paid (input GST credits) — the difference is what you remit to the ATO. Lodgement frequency is quarterly for most sole tradies; monthly for businesses with turnover ≥ $20M; annually if you've elected and are eligible. Quarterly cycles run Jul-Sep / Oct-Dec / Jan-Mar / Apr-Jun, with lodgement due 28 days after each quarter ends.

When you buy materials at a GST-inclusive price (e.g. $1,100 at Reece, $100 of which is GST), if you're GST-registered and the purchase is for business use, you can claim back the $100 GST as an 'input tax credit' on your next BAS. The net effect: GST-registered tradies pay materials at the ex-GST price; unregistered tradies bear the full GST cost themselves. That's the financial argument for voluntary registration even below the threshold.

Most tradie work isn't. The GST-free categories are narrow: basic food, education, healthcare (when supplied by a recognised provider), and certain exports. New residential premises supplied by the developer have specific GST treatment under the margin scheme. If you're doing work that touches one of those categories, talk to an accountant — but for typical residential / commercial trade work, every supply is taxable + 10% GST applies once you're registered.

No — this is a self-help calculator using publicly-published ATO thresholds (current as of 2024–25). Tax thresholds change. Talk to a registered tax agent before making a registration decision worth real money. The ATO's own GST registration page is the authoritative reference; your BAS agent / accountant will tell you the right call for your specific numbers.