Late GST Registration in Australia: Penalties, Interest and How Far Back the ATO Goes (2026)
Part of the guide: The money
There is no late-registration fine in Australia. What there is, in the ATO’s own words, is this: “If you don’t register for GST and are required to, you may have to pay GST on sales made since the date you were required to register. This could happen even if you didn’t include GST in the price of those sales.” So the real cost of registering late is 1/11 of everything you sold in the meantime, paid from your margin instead of by your customers. The penalties and interest come after that, and some of them can be removed on request. Backdating stops at four years.
That ordering matters, because sellers who discover they’ve crossed the threshold usually worry about the wrong thing. The fine is small and formulaic. The interest is mid-sized and partly negotiable. The GST on two years of sales that you never charged anyone is the number that hurts, and it’s the one that’s fixed. Below: what actually happens, the penalties, the interest, the four-year rules in both directions, and the clean-up path with a worked example.
(General information for FY 2026–27, not tax advice for your circumstances. All figures were read on 8 October 2026 from the ATO’s pages on registering for GST, penalty units, failure to lodge, false or misleading statements, penalty relief, general interest charge and GST credit time limits. The A$75,000 threshold is not indexed and may change; the general interest charge rate resets every quarter.)
1. What actually happens if you register for GST late?
You must register within 21 days of your GST turnover reaching A$75,000 on either the current or the projected test. If you don’t, the ATO can treat you as registered from the date you should have been, and GST becomes payable on every sale from that date, whether or not you charged it.
That is the whole mechanism. Nothing about it is discretionary and nothing about it is a “fine”. A seller who registers on time adds 10% to the price and remits 1/11 of the total, so the customer funds the GST. A seller who registers late has already sold at GST-exclusive prices and can’t go back to those customers, so the same 1/11 comes out of what they kept.
For an overseas seller the trigger is sales connected with Australia: goods delivered from Australian stock, and low value goods shipped direct to consumers. Our article on whether foreign companies pay tax in Australia covers the threshold tests and the choice between simplified and standard registration. This one is about what happens once you’ve missed it.
The bill then has four parts: the GST itself, lodgment penalties, possibly a shortfall penalty, and interest. Sections 2 to 4 take them in turn.
2. The penalties: what the ATO can charge, and what it usually does
Two different penalties can apply, and they are often confused. The failure-to-lodge penalty is formulaic and applies to every statement you didn’t lodge. The shortfall penalty is behavioural, runs from 25% to 75% of the tax shortfall, and applies only where you made a false or misleading statement.
Failure to lodge (FTL). “The base FTL penalty is calculated at the rate of one penalty unit for every 28 days (or part thereof) that the document is overdue, up to a maximum of 5 penalty units.” The unit is set by when the infringement occurred:
| Infringement date | Penalty unit | Max per statement (5 units) |
|---|---|---|
| On or after 1 July 2026 | A$364 | A$1,820 |
| 7 November 2024 to 30 June 2026 | A$330 | A$1,650 |
| 1 July 2023 to 6 November 2024 | A$313 | A$1,565 |
The base amount applies to individuals and small withholders. It is doubled for medium withholders and multiplied by five for large ones. A business two years behind on quarterly statements has eight of them, each capped at five units, so the arithmetic can reach five figures. In practice the ATO has discretion to remit FTL penalties, and a seller who comes forward and lodges everything at once is in a much better position to ask than one who waited for the letter.
Shortfall penalties. These attach to a false or misleading statement that produces a tax shortfall, at 25% of the shortfall for failure to take reasonable care, 50% for recklessness and 75% for intentional disregard. A statement you never lodged is an FTL matter, not a shortfall one. Where the ATO does apply a shortfall penalty, the base amount “will generally be reduced if you voluntarily tell us about the error … The BPA may be reduced by 20%, 80% or, in some cases, to nil”, and increased by 20% if you obstructed them or sat on the error. Two cautions from the same page: “Using an agent doesn’t by itself mean you have taken reasonable care”, and the 80% reduction depends on telling them before they tell you.
Penalty relief. For inadvertent errors by entities with turnover under A$10 million, the ATO can waive the penalty during an audit, once every three years at most. “You can’t apply for penalty relief. We will provide it during an audit if it applies to you.” Useful if it happens; not a plan.
3. The interest: GIC at 11.51%, compounding daily, no longer deductible
The general interest charge “is applied to unpaid tax liabilities and is worked out daily on a compounding basis.” For October to December 2026 the rate is 11.51% a year, or 0.03153425% a day. It runs from each statement’s original due date, not from the day you registered.
Three things make GIC the quiet expensive part of a late registration:
- It compounds daily on the GST that was due each quarter, so the oldest quarter has been accruing the longest by the time you catch up.
- It stopped being deductible on 1 July 2025. GIC incurred before then could be claimed; GIC incurred since can’t, so the 11.51% is a true after-tax cost.
- It can be remitted, but only if you ask. “We may remit the GIC if there are extenuating circumstances.” Coming forward voluntarily, lodging everything, and paying or arranging to pay are the usual foundations of that request.
The rate resets each quarter. The quarter before this one was 11.43%, so assume roughly 11% to 12% a year for planning and check the ATO’s rates page for the current figure.
4. How far back the ATO goes, and the four-year credit window that runs the other way
Two four-year rules, pointing in opposite directions. The ATO can’t backdate your registration by more than four years unless there’s fraud or evasion, and before that date “you are not required to be registered”. But your entitlement to GST credits also ceases four years after each statement’s due date, and the ATO has “no discretion to extend” that.
Looking back: four years. “Backdating a GST registration is limited to 4 years. This means, unless there is fraud or evasion: we can’t backdate your GST registration by more than 4 years; you are not required to be registered before that date.” A backdated registration is requested by phone, not online. Separately, the period of review, the window in which the ATO can amend an assessment, is “generally, 4 years from when you lodge your BAS”. If you never lodged, that clock hasn’t started.
The credit window: also four years, and it’s already running. “Your entitlement to a GST credit ceases unless it is included in an assessment before the end of 4-year credit time limit. The 4-year credit time limit ends 4 years after the lodgment due date of the BAS for the tax period in which you could have first claimed the GST credit.” So when you backdate, the credits on your Australian-connected costs for each quarter, import GST, platform fees, advertising, are only yours if that quarter’s statement is lodged in time. The oldest quarter expires first.
This is the “retrospective refund” question in the keyword. Hana runs an Australian-goods exporter: her supplies are GST-free, and her Australian costs carried A$18,000 of GST over four years she never registered for. A registration backdated four years and the back statements lodged promptly produce refunds, because her credits exceed her GST on sales. Wait another year and the oldest quarter’s share is gone, with no way to revive it.
5. The clean-up path: backdate, lodge, disclose, ask for remission
Four steps, in that order. Phone the ATO to backdate the registration to the date you were required to register. Lodge every statement from that date, with the credits in them. Make a voluntary disclosure before the ATO contacts you, because the 80% reduction depends on who speaks first. Then request remission of the general interest charge and the failure-to-lodge penalties, with the reasons.
Here is what the bill looks like with and without that path.
Oliver runs a UK company selling low-value goods direct to Australian consumers through Shopify. His connected sales crossed A$75,000 on the projected test in October 2024. He registers in October 2026, two years later, with A$300,000 of GST-exclusive sales in between and A$2,000 of GST on Australian-connected costs.
| Registered on time (Oct 2024) | Registered two years late (Oct 2026) | |
|---|---|---|
| GST on A$300,000 of sales | A$27,273, charged on top and paid by customers | A$27,273 from his margin, less A$2,000 credits = A$25,273 |
| Failure-to-lodge penalties | None | 8 statements, up to 5 units each at A$330 or A$364: up to about A$13,500, often remitted on voluntary catch-up |
| General interest charge | None | On each quarter’s GST from its due date, compounding at about 11%: roughly A$2,900 |
| Shortfall penalty | None | Only if a statement was false or misleading; if treated as failure to take reasonable care, 25% reduced by 80% on disclosure: about A$1,264 |
| Out of his own pocket | A$0 | About A$29,400 to A$42,900, depending on remission |
Two observations. First, the only line Oliver can’t change is the top one. Everything below it is either removable on request or avoidable by lodging. Second, the whole bottom row exists because he didn’t add 10% to his prices in October 2024. The A$27,273 was always going to be paid; the only question was by whom.
Where it’s worth getting help
If you crossed A$75,000 recently, the free path is short: phone the ATO, backdate to the right quarter, lodge the one or two statements involved, and pay. The interest will be small and the penalties may well be remitted when you ask.
The judgment calls are these:
- Which date. Backdating to the wrong quarter either overpays GST or leaves a gap the ATO will find. The current and projected tests decide it, and for an overseas seller so does which sales were connected with Australia.
- The order of events. A voluntary disclosure lodged after the ATO’s first letter loses most of its value. If you’re reading this because of that letter, the sequence changes.
- The remission case. “Extenuating circumstances” is the test, and how it’s argued, with what evidence of what you’ve since done, is most of the outcome.
- The oldest credits. Every month of delay in lodging the back statements can let a quarter of credits expire that nothing can bring back.
That’s the difference between doing it and doing it right the first time: the seller who phoned the ATO the week they realised, versus the one who received the letter, waited, and then paid the full schedule.
If you’d like that looked at properly, our initial assessment form scopes it in about twelve questions, including when you crossed the threshold and what you’ve sold since, without needing a meeting.
FY 2026–27. General information, not tax advice for your circumstances. Figures are the ATO’s published settings at 8 October 2026; the worked examples are illustrative, the general interest charge rate resets quarterly, and the A$75,000 GST registration turnover threshold is not indexed and may change. Confirm the current figures before relying on them.
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