For self-lodgers, individual income tax returns are generally due by 31 October after the end of the financial year. If you use a registered tax agent, you may be able to access a later lodgement schedule, provided you are added to their client list by the required date and meet the ATO’s eligibility requirements. For self-lodgers with a tax bill, payment is generally due on 21 November if you lodge late, and interest may apply to amounts owing after that date.
Consequences of Missing the Deadline
Failure-to-Lodge Penalty
The ATO can apply a Failure to Lodge (FTL) on-time penalty. For individuals and small entities, the penalty is generally calculated as one penalty unit for every 28 days, or part thereof, that the return is late, capped at five penalty units. Because penalty unit values can change, it is important to check the current ATO rate or speak to a registered tax agent before estimating the potential penalty.
Interest on Unpaid Tax
If you have an amount to pay and miss the payment date, the ATO may apply the General Interest Charge (GIC) to the overdue balance. GIC is calculated on a daily compounding basis and continues until the debt is cleared.
Stronger Compliance Action
If you have multiple overdue tax returns or ongoing non-compliance, the ATO may take further action. This can include reminders, penalties, default assessments or other recovery steps, depending on the circumstances. Lodging as soon as possible is usually the best way to reduce the risk of further action.
If You’re Due a Refund
If your return results in a refund, lodging late may still delay the refund being processed. If you have other overdue returns or unresolved ATO obligations, this may also affect how quickly the matter is finalised.
What To Do If You Missed the Deadline
Lodge As Soon As Possible
Lodging as soon as possible may help reduce penalties, interest and further compliance issues. If you are unlikely to lodge promptly, consider speaking to a registered tax agent for support and to understand whether you may be eligible for an agent lodgement schedule.
Set Up A Payment Plan If Needed
If you cannot pay in full, it is still important to lodge your return. You may be able to arrange a payment plan with the ATO to manage the debt over time. Interest may continue to apply, so it is usually best to repay the amount as soon as possible.
Ask For Help Early
If you’re experiencing financial difficulty, the ATO can consider extra time, payment plans, or remitting penalties/interest in some circumstances. Contact them, or ask your agent to speak to the ATO on your behalf. 
How to Avoid Missing Future Tax Return Deadlines
- Consider engaging a registered tax agent before the lodgement deadline if you need professional support or may require access to agent due dates.
- Keep income records, deduction receipts and work-related expense documents organised throughout the year.
- Budget for any potential tax bill early, especially if you are self-employed, an investor, or expect to have additional income to report.
- Respond to ATO or accountant requests promptly so your return can be prepared and lodged on time.
Griffiths Advisory helps individuals, investors and business owners manage their tax obligations with clear, practical advice. If you have missed the tax return deadline, have overdue returns, or are worried about ATO penalties or payment issues, our team can help you understand your options, prepare and lodge your return, and communicate with the ATO where required. Contact Griffiths Advisory to get your tax affairs back on track and plan ahead for future lodgement deadlines.
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Phil has been the Managing Director of Griffiths Advisory for 29 years, combining his expertise in taxation, business advisory, superannuation, negative gearing, and wealth creation. He also loves an active lifestyle, indulging in surfing, cycling, snowboarding, and spending quality time with his wife and two children.
