Published 2 October 2026 · Stewart Private Accounting
For most Australian businesses, compulsory GST registration starts when GST turnover reaches, or is expected to reach, $75,000. The test looks at turnover rather than profit and uses rolling 12-month periods. Waiting until your annual tax return is prepared can leave the decision too late.
Is the $75,000 threshold based on profit or sales?
GST turnover is a measure of business income with specific exclusions. It is not the amount left after wages, rent and other expenses. Your current GST turnover covers the current month and the previous 11 months. Your projected GST turnover covers the current month and the next 11 months. Consider both tests each month. The ATO explains the exclusions and the circumstances in which projected turnover below the threshold may mean registration is not required in its GST registration guidance.
A sole trader running two activities under the same entity should consider the combined turnover of those activities. Having a separate trading name does not create a separate GST registration threshold.
Can a new contract trigger registration?
Yes. Consider this illustrative example: a Perth consultant has earned $48,000 over the current month and previous 11 months. A new contract means their reasonably expected sales for the current month and next 11 months are now $84,000. Assuming all those sales count towards GST turnover and no exception applies, the projected turnover test triggers registration. The consultant does not wait until actual receipts reach $75,000.
Keep a dated forecast supported by signed contracts, bookings and realistic assumptions. A hoped-for sales target and a supported expectation are different things.
How quickly do you need to register?
You generally need to register within 21 days of becoming required to register. Taxi and ride-sourcing businesses have special requirements regardless of turnover, and registration is also required to claim fuel tax credits. The standard threshold is therefore not the only test. See the ATO’s small business registration course.
If registration is overdue, identify the correct effective date promptly. You may owe GST from when registration was required even if you did not charge it to customers. Do not simply choose today’s date without checking the earlier periods.
What changes once you register?
Review customer contracts and whether quoted prices include GST. For example, if an agreed $1,100 price is GST-inclusive and the sale is wholly taxable, its GST component is $100, calculated as $1,100 ÷ 11. Whether you can change a previously agreed price depends on the contract.
Set up the effective date and correct tax codes in your accounting software, issue appropriate tax invoices and prepare to lodge BAS. Registered businesses can claim eligible GST credits, but private expenses and purchases without GST do not automatically produce a credit. The ATO’s GST credits guidance explains the conditions.
Should you register voluntarily below the threshold?
Compare potential credits with the effect on your prices, customers and administration. Voluntary registration generally requires staying registered for at least 12 months. The decision should reflect your business, rather than assuming registration is always beneficial.
What records should you bring to a review?
- Monthly sales reports for all activities in the entity.
- New contracts and a supported 12-month sales forecast.
- Customer pricing terms, invoices and existing registration details.
- Details of unusual sales, such as a business asset disposal.
Stewart Private Accounting can help review the registration position and organise the ongoing records through our accounting and taxation services and bookkeeping services. Contact our Perth team before your next major contract or invoice.
General information current at 2 October 2026. Your business structure, transactions and circumstances affect the outcome. Obtain advice before acting.



