If you need to fix a mistake on a return you have already lodged, here is how to amend a tax return in Australia: wait for your notice of assessment, then sign in to ATO online services through myGov (or the ATO app), go to Manage tax returns and select Amend next to the income year. You can also ask a registered tax agent to lodge the amendment for you, or send the ATO a paper form or letter.

Amending is free, and for most people it is quicker than they expect. Online requests take about 20 days to process, while paper requests can take up to 50 business days.

Below we cover when you should amend, the time limits, what happens if the change means you owe more tax, and a worked example with the actual numbers.

Item	What applies
When you can amend	After your notice of assessment for that year has been issued and processed
Time limit (individuals)	Generally 2 years from the day after the notice of assessment is sent
Time limit (sole traders)	2 years for 2023-24 and earlier, 4 years for 2024-25 and later
Online processing	About 20 days (myGov, ATO app or registered tax agent online)
Paper form or letter	Up to 50 business days
Cost	No fee to request an amendment
Paper form	Request for amendment of income tax return for individuals (NAT 2843)
If you owe more tax	Treated as a voluntary disclosure, shortfall interest charge may apply

When should you amend your tax return?

You may need to amend if you got something wrong or left something out. Common examples are:

• you answered a question incorrectly
• you left out income, such as bank interest, or a capital gain
• you forgot to claim a deduction or tax offset you were entitled to (our guide on what you can claim on tax is a good checklist)
• your employer finalised or updated your income statement after you lodged, or you received a revised payment summary
• you repaid income you were overpaid

If the ATO made the error, contact the ATO first. It may be able to fix it without you lodging an amendment. You don’t need to lodge a fresh tax return to correct a mistake unless the ATO asks you to.

How do you amend a tax return online?

The ATO says online is the fastest way to amend, and you can use it no matter how you lodged your original return. The steps are on the ATO page How to request an amendment to your tax return.

Using myGov

1. Sign in to myGov and select ATO from your linked services.
2. Select Manage tax returns from Quick links.
3. Select Amend next to the income year you need to fix.
4. Change the figures that are wrong. To change an existing amount, select the field and overwrite it.
5. To add a new type of income, deduction or offset, go to the Personalise return screen and tick the relevant box.
6. To add an income statement, interest or dividend record, or another deduction, use the Prepare return screen and select Add/Edit for that section.
7. Check the summary and submit.

Using the ATO app

Log in, select View next to Your tax return, then View tax return, then Amend. The editing steps are the same as in myGov.

What are the other ways to amend a tax return?

• Registered tax agent: your agent can lodge the amendment electronically, even if your original return wasn’t lodged that way. Agents can also use the paper form for tax professionals, which takes up to 50 business days.
• Paper form: use the Request for amendment of income tax return for individuals (NAT 2843). You must sign it if you fill it in yourself. Allow up to 50 business days.
• Letter: include your TFN, full name, postal address, a daytime phone number, your bank account details, the income year, the question number and description, the amounts you are adding or taking away, the reason for the change, copies of supporting documents, and a signed and dated declaration. Post it to Australian Taxation Office, PO Box 3004, PENRITH NSW 2750. Allow up to 50 business days.

How long do you have to amend a tax return?

The clock starts the day after your notice of assessment is sent, not the day you lodged. The ATO’s own example: if your notice was sent to myGov on 3 November 2026, your amendment period starts on 4 November 2026 and ends on 4 November 2028. Our guide to the notice of assessment shows where to find that date.

Taxpayer	2023-24 and earlier	2024-25 and later
Individuals (not in business)	Generally 2 years	Generally 2 years
Sole traders	Generally 2 years	4 years
Businesses with aggregated turnover under $50 million	Separate business rules apply	Up to 4 years

You can make more than one amendment request within the period. The ATO itself generally can’t amend your assessment more than 2 years after it was issued unless you ask it to, although there are exceptions such as fraud or evasion. Sources: ATO time limits on amendments and changes to the amendment period for business.

If you never lodged the return in the first place, that is a different problem. See our guide to a late tax return.

What happens after you lodge an amendment?

The ATO issues an amended notice of assessment. What happens next depends on which way the numbers move.

• Your tax goes down: you get a refund, unless you have other tax debts it can be used to pay.
• Your tax goes up: the ATO treats the amendment as a voluntary disclosure. You will need to pay the extra tax, and shortfall interest charge (SIC) may apply.

Penalties when you owe more

Telling the ATO yourself usually works out much better than waiting for it to find the error. Under the ATO’s voluntary disclosure rules:

• any penalty is reduced by 80% if you disclose before the ATO tells you it will examine your affairs
• the penalty is reduced to nil if the shortfall is less than $1,000, you disclose before the ATO tells you about an examination, and no public request for voluntary disclosures applies
• a 20% reduction may apply if you disclose after being told of an examination and your disclosure saves the ATO significant time or resources

Shortfall interest charge

SIC applies when an amendment increases your tax. It compounds daily and is set at the 90-day Bank Accepted Bill rate plus 3%. The annual SIC rate is 7.43% for July to September 2026 and 7.51% for October to December 2026.

Worked example: amending to fix two mistakes

The facts

Mia is an Australian resident employee. She lodged her own 2025-26 return in July 2026 showing taxable income of $72,000, and her notice of assessment has been issued. She then realises two things: she forgot $1,200 of work-related expenses (see our list of work-related tax deductions), and she left out $2,000 of bank interest.

The figures below use the 2025-26 resident tax rates plus the 2% Medicare levy. They ignore other offsets and levies. At these incomes the low income tax offset is nil because it cuts out at $66,667.

Step	As lodged	After amendment
Taxable income	$72,000	$72,800 ($72,000 – $1,200 + $2,000)
Income tax ($4,288 + 30% over $45,000)	$4,288 + $8,100 = $12,388	$4,288 + $8,340 = $12,628
Medicare levy (2%)	$1,440	$1,456
Total	$13,828	$14,084

Option 1: amend for the deduction only

If she only claims the missed deduction, taxable income drops to $70,800. Tax is $4,288 + 30% x $25,800 = $12,028, plus Medicare levy of $1,416, giving $13,444. That is $384 less than the $13,828 she was assessed, so she would get $384 back. But she would still have income missing from her return.

Option 2: amend for both items

Fixing both items, her total rises from $13,828 to $14,084, so she owes an extra $256 ($640 more tax on the interest, less $384 saved on the deduction). Because the shortfall is under $1,000 and she is telling the ATO before any examination, any penalty would be reduced to nil. SIC may still apply on the $256. This is the right choice: it fixes the whole return in one request.

Want to test your own numbers first? Try our tax refund calculator.

When do you need an objection instead?

An amendment fixes your own mistakes. You need to lodge an objection instead if you want to dispute the law or the facts the ATO used in a decision, or if you are outside the amendment time limit. Most individuals have 2 years to object to an income tax assessment, and you may be able to ask for an extension of time (ATO: what you can object to and the time limits). Our ATO dispute resolution service can help if you are in this position.

Frequently asked questions

Talk to a registered tax agent

If you are not sure whether to amend, object or leave things as they are, a registered tax agent can review your return and lodge the change for you. Call Nanak Accountants & Associates on 1300 626 258 or book a consultation with our team. We can help through our individual tax return service and, if you run a business, our sole trader accounting service.

This article is general information only and is not personal financial or tax advice. Information checked against ATO sources on 9 October 2026.