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Self-assessment and the taxpayer

Find out how the self-assessment system works and what to do if you need to correct an error.

Last updated 20 June 2024

How the self-assessment system works

Australia's income tax system works on self-assessment. This means, we accept the information you give us is complete and accurate. We will review the information you provide if we have reason to think otherwise.

The self-assessment system places the responsibility on you to ensure your tax return and other tax forms comply with taxation laws. You must report all your assessable income and only claim deductions and offsets to which you are entitled.

We assume you complete your tax return and other forms in good faith and accept the information you provide as being true and correct. To ensure the integrity of the tax system, the law provides us with a period where we may review a return and may increase or decrease the amount of tax payable.

This period of review depends on a number of factors, including whether or not you are in business and whether tax was avoided as a result of a scheme or fraud.

Find out about income tax decisions you can object to and time limits.

You can self-assess your liabilities or entitlements under the laws applying to:

For more information about indirect taxes, see Guide to self-assessment for indirect taxes.

How to correct an error

When you sign your tax return and other forms, you are taking responsibility for the claims you are making. If you become aware that your tax return is incorrect, you must contact us as soon as possible to amend the error.

Where we detect errors, we may issue an amended assessment. You must then repay any tax owing, and interest and penalties we apply under the law. If you have overpaid your tax, we will pay you interest on the overpayment.

You will not be subject to penalties if you base your tax claim on wrong information in one of our publications. However, interest could be payable depending on the circumstances of the case.

If you make a voluntary disclosure in the approved form to tell us about mistakes in your tax affairs, usually there is concessional treatment for penalties and interest charges. This may occur even where the error increases your tax or decrease your credits.

We can help you to get it right

Whether you prepare your own return or pay a registered tax agent to do it for you, we provide information to help.

If you're lodging your own tax return, you can lodge your tax return online with myTax. Helpfiles for myTax are available from the help function when you are completing the form. We also provide individual tax return instructions and supporting publications on our website.

In addition, we provide guidance in the form of public rulings and product rulings. If your situation is not covered in these publications, you can request a private ruling.

People with low incomes can get help and support to complete their tax return from our Tax Help program.

If you take reasonable care with your tax affairs, you will not incur a penalty for honest mistakes. You may still be liable to pay interest on any amounts of underpaid tax.