The self-lodgement tax deadline falls on 31 October every year, closing the four-month window that opened on 1 July. 31 October 2027 falls inside October, the final month of that window, in the fourth calendar quarter of 2027, with the deadline drawing closer as the month progresses.
A public holiday that falls on a Sunday sits inside the weekend rather than beside it, and whether a substitute day off applies to the following Monday depends on the specific holiday and the state. Sunday 31 October 2027 falls on this day of the week, at the close of the weekend, immediately before the working week resumes.
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 2027 can show a different total depending on which state's calendar applies to 31 October. Interstate businesses need to check more than one state's list before setting a national deadline.