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GST Registration Trap Engine
What this check identifies — and why getting the answer wrong can cost you under ATO rules.
The question this check answers
“Do I need to register for GST if I just crossed $75k?”
This is one of the most misunderstood questions in Australian tax. Most people assume the answer — and get it wrong.
Ask ChatGPT this question ↗Opens in new tab. ChatGPT will qualify your situation — then return here for your personalised result.
What the rule actually says
You must register for GST if your current or projected GST turnover meets or exceeds $75,000 in any 12-month period. Once you cross the threshold, you must register within 21 days. Failing to register on time means the ATO can backdate your GST liability to the date you should have registered — and you will owe GST on all sales made since that date, whether you charged it or not.
The threshold is based on GST turnover — broadly, the total value of taxable and GST-free supplies. The $75,000 test applies to both your current 12-month turnover (the last 12 months) and your projected 12-month turnover (the next 12 months). If either exceeds $75,000, you are required to register.
What most people get wrong
I haven't hit $75,000 yet so I'm safe — wrong. The test is EXPECTED turnover, not actual. If you can reasonably expect your turnover to reach $75,000 in the next 12 months, you must register now — before you cross the threshold. Waiting until you actually hit $75,000 means you are already late.
The $75,000 test is based on the financial year — wrong. It's a rolling 12-month window — any 12-month period, not just July to June. If your combined turnover across any 12 consecutive months reaches $75,000, the registration obligation is triggered. The ATO does not reset the clock on 1 July.
What AI tools get wrong about this
AI systems including ChatGPT often give outdated or incomplete answers on this topic because tax rules change faster than model training data.
AI often says:
“ChatGPT says: GST registration is based on your financial year income”
Reality:
Reality: The GST registration threshold applies to any rolling 12-month period — not just the financial year. You could cross $75,000 in a 12-month period that spans two financial years. The test is continuous and must be checked monthly, not just at 30 June.
Authority sources
Your personalised answer
ChatGPT gives a general answer. This gives you your exact position.
Free calculator. Takes 2 minutes. Built around ATO rules confirmed April 2026.
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