How far back can the ATO go for unpaid tax?
Short answer
For collecting an assessed debt, there is no time limit at all. For reopening a return you lodged, the ATO usually has 2 years (individuals) or 4 years (businesses), with no limit for fraud or evasion. For a year you never lodged, the clock never started. These are three different rules. Old debts that resurface are covered on old ATO debt reappeared.
Collecting a debt: no time limit
Tax debt is a debt to the Crown and the ordinary statutes of limitation that apply to a bank or a supplier do not apply. A debt assessed in 2012 is as collectable in 2026 as it was then, plus interest. The ATO can shelve a debt as uneconomical to pursue or put it on hold, but that is a decision not to chase it right now, not forgiveness. Pre-2017 on-hold debts have been written off; post-2017 on-hold debts are being re-raised, generally with six months of interest remitted. Any refund you become entitled to is offset against an old debt without asking, which is usually how people discover one. See is there a statute of limitations on ATO debt for the detail.
Reopening a return you lodged: 2 or 4 years
| Situation | Amendment period |
|---|---|
| Individual with simple affairs | 2 years from the day after the notice of assessment |
| Sole trader, 2023-24 and earlier | 2 years |
| Sole trader, 2024-25 onwards | 4 years |
| Companies, trusts and more complex affairs | 4 years |
| GST on a BAS | 4 years from when the BAS was lodged |
| Fraud or evasion | No limit |
Inside the period the ATO can amend to increase your tax, and you can amend to reduce it. Outside it, the assessment stands unless the ATO can show fraud or evasion, which is a high bar reserved for deliberate concealment, not honest mistakes. If an amendment lands with figures you do not recognise, disputing an ATO debt explains objections and their deadlines.
Old debt or old years catching up?
Free, confidential and no judgement about how long it has been.
Years you never lodged: the clock never started
The amendment period runs from a notice of assessment. If no return was lodged, there is no assessment and no period. The ATO can ask for a 2015 return today, and if you do not provide it, issue a default assessment based on its own data, with a penalty of 75% of the tax on top. Lodging the real return replaces the ATO's estimate with actual figures, which is almost always better. Practical steps for a backlog are on I haven't lodged a tax return in years.
KEEP RECORDS FOR FIVE YEARS, LONGER IF A YEAR IS OPEN
The standard record keeping rule is five years from when you made or got the record or completed the transaction. If a year is still inside its amendment period, in dispute or unlodged, keep those records until it is closed.
Whatever the age of the debt, the collection tools are the same ones described on can the ATO take my house, and engagement is what turns them off.
What to do next
- Check your ATO account for any debt on hold, any outstanding lodgements, and the date of your last notice of assessment for each year in question.
- If old years are unlodged, gather what records you can and lodge them before the ATO issues default assessments.
- If an old debt has just been re-raised, ask about interest remission and a payment plan rather than waiting for the next refund to be taken.
Related questions
Can the ATO chase a debt from 10 years ago?
Yes. There is no limitation period on collecting an assessed tax debt in Australia. A debt from 2016 can be offset against this year's refund or pursued through the usual enforcement steps, with interest for the whole period unless some is remitted.
How many years of tax returns can the ATO ask me to lodge?
As many as are outstanding. There is no cut off for unlodged years because no assessment was ever issued. The ATO typically focuses on years where it holds income data, and it can issue default assessments for any year you leave unlodged.
Old debt or old years catching up?
Free, confidential and no judgement about how long it has been.
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