Penalties for Getting Your Tax Return Wrong in Australia 2026–27

Getting a tax return wrong does not automatically mean a fine. The ATO processes a huge volume of returns, and most honest slip-ups are fixed with an amendment rather than a penalty. The line sits between a genuine error and behaviour the ATO treats as careless, reckless or deliberately misleading. Cross that line and the cost stops being theoretical.

This guide breaks down how the penalty system works, what the published figures look like, how interest fits in, and what to do if you realise something on your return is wrong. Where a number is indexed or reviewed each year, that is flagged so you can confirm the current figure with the ATO before you rely on it.

What the ATO means by a wrong return

Much of the penalty framework hangs off a single idea: a false or misleading statement. A 2004 Treasury review of income tax self-assessment described the penalties that apply in these circumstances as tax shortfall penalties, and tied them directly to making a false or misleading statement.

In practice a return can become false or misleading in a few broad ways:

• Income is left out, whether deliberately or because a payment summary or side income was overlooked.

• A deduction is claimed that the taxpayer was not entitled to, or was claimed at the wrong amount.

• Information is entered incorrectly, including under the wrong label.

• A document or statement is not lodged at the appropriate time.

Notice that intent is not the trigger. An accidental error can still produce a shortfall penalty if the taxpayer did not take reasonable care to get it right, which is why record keeping matters more than most people expect.

How shortfall penalties are scaled

The ATO does not apply one flat rate for every wrong return. The penalty scales with the behaviour behind the error, so the more deliberate the mistake, the heavier the consequence.

The behaviour tiers

ATO audit penalty material lists the tiers as 20 penalty points for failure to take reasonable care, 40 penalty points for recklessness, and 60 penalty points for intentional disregard. A separate 2026 guide on ATO penalties describes incorrect information penalties as ranging from 25% to 75% of the tax shortfall. The two descriptions are directional rather than identical in wording, so use them to understand the shape of the scale rather than as a precise calculator, and confirm current published rates with the ATO.

Where the 75% figure appears

One accounting source notes that in certain failure-to-lodge situations, a penalty of 75% of the tax-related liability can apply. That is the top end of the scale and it is reserved for the most serious conduct. You should check the specific conditions with the ATO, because the exceptions and thresholds attached to that figure are detailed.

Late lodgment penalties and the penalty unit

Missing a due date is a separate issue from getting the content wrong, and it comes with its own arithmetic. Late lodgment penalties are calculated in penalty units, and the unit value is indexed over time.

Sources covering the 2026 lodgment period cite each penalty unit at $330 for 2025 to 2026, meaning a single late return can move from $330 up to $1,650 as the penalty escalates. Because the unit value changes with indexation, the dollar figures for the 2026–27 income year should be confirmed against the ATO's current penalty unit page before you treat them as final.

The important takeaway is structural rather than numerical. A late return is not a one-off fee. It can grow the longer the return stays outstanding, and it applies on top of any shortfall penalty the content of that return attracts.

Interest charges sit alongside penalties

Penalties are only part of the bill. When inconsistencies are identified in a return, further action may include a reassessment, interest charges, and financial penalties depending on the circumstances. Interest is calculated on the tax that should have been paid, which means a wrong return can cost more than the penalty amount alone.

This is why a small error that shifts tax payable by a modest amount can compound into a noticeably larger debt if it takes a couple of years to surface.

Fixing a mistake before the ATO finds it

Amending a return is not the same as being audited, and it does not automatically trigger a penalty. Community guidance from the ATO's own forums makes the position fairly clear: no one can say in advance whether the ATO will impose a penalty on an amended return, and if a penalty is imposed, the taxpayer can request that it be remitted.

That is a reasonable summary of how most straightforward corrections play out. A taxpayer who notices an error, lodges an amendment promptly and can explain what happened is in a different position to someone whose error only comes to light through ATO data matching. The first group usually has more room to argue that they took reasonable care.

If you receive a letter asking you to amend, the practical response is to check the information being queried, correct the return through your tax agent or myGov, and keep a copy of the correction and any supporting records in case the matter is reviewed again.

Penalty relief and remittance

There is a formal relief pathway. The ATO announced on 4 July 2018 that it would provide penalty relief to eligible individuals and entities with an annual turnover below a specified threshold, aimed at inadvertent errors. Eligibility depends on the turnover threshold and the nature of the mistake, so the specifics are worth checking directly rather than assuming you qualify.

Remittance is the broader mechanism. If a penalty is applied and you believe it is unfair or disproportionate, you can ask the ATO to remit it. A request generally works better when it explains the circumstances, shows what steps you took to get the return right, and demonstrates that the error was not part of a pattern.

Record keeping is the cheapest defence

Almost every penalty conversation comes back to evidence. A deduction you can substantiate is hard to dispute. A deduction you cannot substantiate is a shortfall waiting to be found, and the behaviour tiers mean the difference between a 20-point and a 60-point outcome often comes down to whether you kept records.

Lodgya is a browser-based income and expense record-keeping tool built in Melbourne by founder Omar Mulabegovic to address exactly that problem. It provides a personal tax tracker for deductions and work-related expenses, a rental property tracker with depreciation and accountant-ready PDF reports, and a business tracker with a mileage logbook and GST and BAS reconciliation. The free tools include a tax refund estimator, a working-from-home calculator, a car logbook and cents-per-kilometre calculator, and an ATO-focused tax calendar.

To be clear, Lodgya is not tax advice and not a registered tax agent. It does not lodge returns for you and it does not guarantee an outcome. What it does is keep the receipts, recurring transactions and records in one place so that when you or your accountant complete the return, the numbers are defensible.

What to do if you get an ATO letter

1. Read the letter properly and note the response date.

2. Check whether it is a request for information, a proposed amendment, or a penalty notice.

3. Gather the records behind the item being queried.

4. Correct the return if it is wrong, and keep proof of the correction.

5. If a penalty is applied and you disagree, lodge a remittance request with your reasoning.

6. Speak to a registered tax agent if the amount or the conduct allegation is significant.

Frequently Asked Questions

Will the ATO penalise me for a small mistake on my tax return?

Not automatically. Shortfall penalties attach to false or misleading statements, and the scale depends on whether the ATO considers the error careless, reckless or deliberate. A small, genuine error that you correct promptly is more likely to be resolved through an amendment. If a penalty is applied, you can request remittance.

Can I fix my return before the ATO notices?

Yes, you can lodge an amendment. ATO community guidance notes that no one can say in advance whether a penalty will be imposed on an amended return, and that any penalty can be contested through a remittance request. Acting early generally puts you in a stronger position than being caught by data matching.

How much is a penalty unit worth?

Sources covering the 2026 lodgment period cite $330 per penalty unit for 2025 to 2026, with a single late return ranging from $330 to $1,650. The unit value is indexed, so the figure for the 2026–27 income year should be confirmed on the ATO website before you rely on it.

Can the ATO waive a penalty if the mistake was an accident?

Possibly. The ATO announced on 4 July 2018 that it would provide penalty relief to eligible individuals and entities with turnover below a threshold for inadvertent errors. Eligibility depends on your circumstances. Even where relief does not apply, you can still ask for the penalty to be remitted.