This article provides general information only and does not constitute personal financial advice. It has been prepared without taking into account your objectives, financial situation or needs. Before acting on any information in this article, you should consider whether it is appropriate for you and seek advice from a licensed financial adviser or registered tax agent if necessary.

If you lodge your own individual tax return in Australia, the deadline to submit it to the Australian Taxation Office (ATO) is October 31. This date applies to the tax return for the financial year ending the previous June 30. However, if you engage a registered tax agent to prepare and lodge your return, you automatically receive an extension—often until March 31 or May 15 of the following year, depending on the agent’s lodgment program with the ATO.

Understanding whether you need to lodge by October 31 or qualify for the extended deadline can save you from late lodgment penalties and help you organise your tax affairs more effectively.

Who Must Lodge by October 31

October 31 is the firm deadline for Australian resident individuals who prepare and lodge their own tax return. This applies whether you use myTax (the ATO’s free online lodgment service), paper forms, or commercial tax preparation software to submit your return directly to the ATO.

According to the Australian Taxation Office, this deadline covers the financial year from July 1 to June 30 (ATO, 2026). For example, the October 31, 2026 deadline applies to the 2025-26 financial year (ended June 30, 2026). If you miss this date and lodge late without a valid reason or an agent extension, you may face a failure-to-lodge penalty, which can start at several hundred dollars and increase depending on how late the return is and the amount of tax owed.

The October 31 deadline applies to most individual taxpayers, including employees, sole traders, and investors who lodge their own returns.

Who Qualifies for an Automatic Extension

If you engage a registered tax agent to prepare and lodge your return on your behalf, you receive an automatic extension. The exact extended deadline depends on the agent’s lodgment program with the ATO, but it typically falls between March 31 and May 15 of the year following the original October 31 deadline.

For instance, if you appoint a registered tax agent for your 2025-26 tax return (due October 31, 2026), your lodgment deadline may be extended to March 31, 2027 or May 15, 2027, depending on the agent’s arrangement with the ATO.

This extension applies automatically once you have formally engaged a registered tax agent. You do not need to apply separately to the ATO for the extension—it is granted as part of the agent’s lodgment program. However, you must have engaged the agent before the original October 31 deadline to benefit from the extension for that year.

What Is a Registered Tax Agent

A registered tax agent is a professional authorised by the Tax Practitioners Board (TPB) to provide tax agent services in Australia. Registration with the TPB is a legal requirement, and only registered agents may charge a fee to prepare and lodge tax returns on behalf of others.

Registered tax agents are subject to the Tax Agent Services Act 2009 and must meet minimum qualifications, professional indemnity insurance requirements, and continuing professional education obligations. They are also bound by a Code of Professional Conduct, which includes duties such as acting lawfully, with honesty and integrity, and in the best interests of clients.

Read also: How Australian Income Tax Brackets Work: The Marginal Rate System Explained Step by Step

You can verify whether a tax agent is registered by searching the TPB Public Register online. This register shows the agent’s registration number, registration status, and any conditions or disciplinary history.

When to Use a Registered Tax Agent vs DIY

Choosing between lodging your own return by October 31 or engaging a registered tax agent depends on the complexity of your tax affairs and your confidence in preparing an accurate return.

Using myTax or commercial software is generally suitable if your tax situation is straightforward: you earn salary or wages, have standard deductions (such as work-related expenses or donations), and receive pre-filled information from employers and financial institutions. myTax is free, guides you through each section, and pre-fills much of your information.

A registered tax agent may be worth considering if you have multiple income sources (such as rental property income, share dividends, or business income), significant deductions, capital gains or losses, or if you are uncertain about how to correctly report certain items. Agents can also help you identify legitimate deductions you may have overlooked and minimise the risk of errors that could trigger an ATO review or audit.

The cost of a tax agent varies depending on the complexity of your return, but it typically ranges from a few hundred dollars for a simple return to over a thousand dollars for complex tax affairs involving trusts, businesses, or investment structures. As covered in foundational texts such as Principles of Finance (OpenStax, 2022), understanding the cost-benefit trade-off of professional advice is an important part of managing your financial responsibilities.

What Happens If You Miss the Deadline

If you lodge your own return after October 31 without a valid reason or an agent extension, the ATO may issue a failure-to-lodge penalty. The penalty amount depends on the size of your tax debt and how late the return is. Even if you do not owe any tax (or are due a refund), late lodgment can still attract a penalty and may affect your ability to access certain government payments or services.

If you have a valid reason for lodging late—such as serious illness, natural disaster, or other circumstances beyond your control—you can request a penalty remission by contacting the ATO and explaining your situation.

Practical Next Steps

If you plan to lodge your own return, aim to complete it well before October 31 to allow time for any issues or queries. Gather your income statements (payment summaries, dividend statements, and interest statements), receipts for deductions, and private health insurance statement before you start. Most of this information will be pre-filled in myTax from mid-July onward.

If you prefer to use a registered tax agent, engage one as early as possible (ideally before October 31) to secure the extended lodgment deadline and give the agent sufficient time to prepare an accurate return. Ask about their fees upfront, verify their registration with the TPB, and provide all requested documentation promptly.

Whichever route you choose, lodge on time to avoid penalties and keep your tax affairs in good standing with the ATO. Current lodgment deadlines, penalties, and agent lodgment programs are subject to change, so verify the latest information at ato.gov.au before finalising your plans.