You must register for GST once your business turnover reaches $75,000 over a 12-month period, or once you expect it to. Below that, registering is your choice. A few activities force you to register from the first dollar, no matter how little you earn.
The $75,000 is turnover, not profit
The threshold is measured on GST turnover, which is your gross business income before you take out a single expense, and it leaves GST itself out. A business turning over $80,000 with $50,000 of costs still has to register, because the test looks at the $80,000, not the $30,000 left over. Owners who fixate on profit miss this and cross the line without noticing.
Two ways to cross the line
There are two, and the second one catches people out. Current turnover is this month plus the previous 11. Projected turnover is this month plus the next 11. You register if either one reaches $75,000. Sign a contract today that will clearly push the coming year over the threshold, and you are required to register now, not when the money lands.
You get 21 days, then it hurts
Once you cross or expect to cross, you have 21 days to register. Miss it and the ATO can backdate your registration to the date you should have registered. That is the part that stings. You then owe GST on every sale since that date whether or not you charged it. On $80,000 of sales that is about $7,270 out of money you have already spent, plus possible penalties and interest.
Some businesses get no threshold at all
Taxi, limousine, and ride-sourcing drivers, which covers Uber, DiDi, Ola and the rest, must register from their first fare, even for a few hours a week. Anyone claiming fuel tax credits has to be registered too. Non-profit bodies get a higher threshold of $150,000 instead of $75,000.
Under the threshold, it is a real decision
Below $75,000 it is a genuine choice, not a formality. Registering voluntarily lets you claim back the GST on your business purchases. If you have just spent big on tools, equipment, or a vehicle, that 10% back can be worth more than the paperwork costs you. It can also read as more established to larger clients, who often expect their suppliers to be registered and can claim your GST back anyway.
The cost sits on the other side. Once registered you charge 10% on your sales, which bites if your customers are ordinary consumers who cannot claim it back, making you dearer or eating your margin. You also commit to lodging a BAS every quarter and staying registered for at least 12 months. For a business selling mostly to the public with low expenses, staying under the threshold and out of the system is often the better call.
When I would register early, and when I would wait
I would register early if most of my customers were GST-registered businesses, if I had heavy start-up costs with GST on them, or if I could see $75,000 coming and wanted clean records from day one. I would wait if I sold to consumers, kept expenses low, and had no near-term sign of crossing. If you do register, the next job is lodging the BAS on time, and HPLedger tracks GST as you go so the quarterly return is a review rather than a scramble.
Short version. Over $75,000, heading there, or driving for a rideshare app, and it is not a choice. Under that, weigh the GST you would claim back against the GST you would have to charge and the BAS you would have to lodge. The answer swings on who your customers are and how much GST you are paying out.
Technical reference
Requirement to register. An entity carrying on an enterprise must register for GST if its GST turnover meets the registration turnover threshold. A New Tax System (Goods and Services Tax) Act 1999 (GST Act), s 23-5.
Registration turnover threshold. $75,000 for most entities; $150,000 for non-profit bodies. GST Act s 23-15 and the GST Regulations. The $75,000 threshold has applied since GST commenced on 1 July 2000.
GST turnover tests. Division 188 GST Act. Current GST turnover is the current month plus the previous 11 months (s 188-15); projected GST turnover is the current month plus the next 11 months (s 188-20). Both exclude input-taxed supplies, sales of capital assets, and supplies made in ceasing or substantially reducing an enterprise.
Timing. You must apply within 21 days of becoming required to register. GST Act s 25-1. Registration can be backdated, limited to 4 years.
Register regardless of turnover. Suppliers of taxi travel, which the ATO treats as including ride-sourcing, must be registered (GST Act s 144-5). Entities claiming fuel tax credits must be registered.
Voluntary registration. An entity below the threshold may register voluntarily (GST Act s 23-10) and must generally stay registered for at least 12 months.
Rate and mechanics. GST is 10%; the GST in a GST-inclusive price is 1/11 of that price. Registered entities charge GST on taxable supplies, claim GST credits on creditable acquisitions, and report through a BAS.
Currency. Current as at July 2026.
