Missed the 21-day window after crossing A$75,000? Here’s what the ATO does next and how to limit the damage.
Last updated: June 2026
The ATO backdates your effective GST registration date to when you should have registered — 21 days after your GST turnover exceeded A$75,000 — and you owe GST on your taxable sales from that date forward, whether or not you actually charged customers GST at the time. If you didn’t add GST to your invoices during the period you were late, you generally still owe the ATO that amount out of your own revenue.
Beyond the backdated GST itself, the ATO can apply a failure to lodge (FTL) penalty and general interest charge (GIC) on the outstanding amount, calculated based on how late you were and your compliance history. Penalty amounts are generally calculated per penalty unit for each 28-day period the failure continues, up to a maximum, and the ATO has discretion to remit penalties in cases of genuine, promptly self-corrected mistakes.
Not automatically — the ATO has discretion, especially for genuine, promptly self-disclosed mistakes. But GST owed and interest generally still apply regardless of any penalty remission.
Generally yes. Your registration is backdated, and you’re liable for GST on sales made from that date, meaning you effectively absorb it unless you go back and separately invoice customers.
This is treated more favourably than deliberate avoidance, especially if you disclose it yourself promptly rather than waiting for an ATO review to catch it.
Yes, you can request remission of penalties and interest, and if unsuccessful, formally object to the ATO’s decision through the standard objection process.
Track your rolling 12-month GST turnover regularly rather than just at tax time — our GST threshold checker can help you monitor this.
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