You have two years to fix a tax return. Here is how the clock works.

Individuals generally have two years from the date their notice of assessment issues to request an amendment. That date is printed on the assessment itself and the window runs from there, not from the end of the financial year or the date you lodged.

For most people that means a return lodged in August is amendable until roughly the August two years later. Sole traders and small business have four years from the 2024-25 income year. Once the period closes, the return generally cannot be amended and an overpayment stays with the ATO.

If you are not sure when your assessment issued, the date is on the notice itself and in your ATO online account under your lodgement history. Working out where each year sits is the first thing a registered tax agent does in a review and it costs nothing to ask.

Where to find the date

It is printed at the top of the notice of assessment the ATO issued after you lodged and it is listed against each year in your ATO online account under your lodgement history. If you lodged several years at once, each has its own assessment date and therefore its own window. Ten minutes with those dates tells you which years are still open.

What closes when the window closes

After the amendment period ends, the return generally cannot be amended, whether the change would go in your favour or the ATO's. An overpayment stays where it is. There are narrow circumstances in which a longer period applies or the ATO agrees to extend one, but they are exceptions and not something to plan around. A registered tax agent will tell you where a year sits before anything else happens.

Why checking earlier is better

Because the clock runs from the assessment date, the most recent year has the most time left and the oldest has the least. People who wait until a year is almost closed lose the option of taking their time over records. If a year is close to the edge, say so when you enquire and the agent will confirm the date first.

What to do now

Tell us the income years you have lodged and what you do for work. A registered tax agent in the Untax network contacts you, confirms their registration and, with your authority, reviews the return. The review is free and nothing is lodged without your written approval.

General information only. It does not take account of your circumstances and is not tax advice. Untax is a marketing and referral service and is not a registered tax agent.