If you lodge your own 2025-26 tax return, it is due by 31 October 2026. That is a Saturday this year, and under the ATO's weekend rule a due date that falls on a non-business day moves to the next business day — Monday 2 November 2026. Miss it and you risk a failure-to-lodge penalty of $364 for every 28 days, and interest on any tax you owe at 11.51% a year for October–December 2026.
2025-26 tax return: the dates and the cost of missing them
| What changed | Before | Now |
|---|---|---|
| Self-lodgment due date | — | 31 October 2026 (lodge by 2 November 2026) |
| Via a registered tax agent (most people) | — | 15 May 2027, if on the agent's list by 31 October 2026 |
| Failure-to-lodge penalty | — | $364 per 28 days late, max $1,820 |
| General interest charge, October–December 2026 | 11.43% | 11.51% |
| Typical online refund | — | within 2 weeks |
Two ways to get more time
The simplest is a registered tax agent. If you are on an agent's client list before 31 October 2026, most people's 2025-26 return is not due until 15 May 2027. The ATO warns that first-time clients, or anyone changing agent, should contact the agent before 31 October. Some clients get an earlier date — for example 31 March 2027 if their latest return had a tax liability of $20,000 or more.
The other is the weekend rule. The ATO says that when a lodgment or payment due date falls on a day that is not a business day, you can lodge or pay on the next business day, which this year gives self-lodgers until Monday 2 November 2026. Don't plan around the last day: myTax pre-fill has been ready since late July, and most online returns are processed in about 12 business days.
What lodging late costs
The failure-to-lodge penalty is one penalty unit — $364 for failures on or after 1 July 2026 — for every 28 days or part of 28 days the return is overdue, up to five units ($1,820) for an individual. A return 10 days late would attract $364; 60 days late, $1,092. The ATO says it generally does not apply the penalty for an isolated late lodgment, and warns you and issues a notice to lodge before it does.
Interest is the bigger risk if you owe tax. The general interest charge compounds daily and resets each quarter; the ATO has set it at 11.51% for October–December 2026, up from 11.43% for July–September 2026, with a daily rate of 0.03153425%. On a $2,000 bill left unpaid for 30 days, that is about $19.01 — and GIC incurred from 1 July 2025 can't be claimed as a tax deduction.
Check your refund before you lodge
The 2025-26 return uses last year's tax rates, not the 2026-27 ones now in your pay. Our tax return calculator estimates your refund or bill on 2025-26 rates, and the 2026 tax return guide covers what's new, including the 70c work-from-home rate and 88c per kilometre for car expenses. Every other date for the year is on our tax calendar.