The self-lodgement tax deadline falls on 31 October every year, closing the four-month window that opened on 1 July. 25 October 2026 falls inside October, the final month of that window, in the fourth calendar quarter of 2026, with the deadline drawing closer as the month progresses.
Any deadline or bill payment due on Sunday 25 October 2026 moves to the following Monday under standard business-day rules, since Sunday sits outside the working week this page counts by default. This convention applies consistently across contracts, invoices and statutory deadlines throughout Australia, regardless of which state or territory is involved.
The working-day count on this page excludes both weekend days and any public holiday declared for the state selected, so the same date in 2026 can show a different total depending on which state's calendar applies to 25 October. Interstate businesses need to check more than one state's list before setting a national deadline.
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