The self-lodgement tax deadline falls on 31 October every year, closing the four-month window that opened on 1 July. 12 October 2030 falls inside October, the final month of that window, in the fourth calendar quarter of 2030, with the deadline drawing closer as the month progresses.
Any deadline or bill payment due on Saturday 12 October 2030 moves to the following Monday under standard business-day rules, since Saturday is not a working day for the Monday-to-Friday workforce this page counts by default. Shift-based industries follow their own separate rostering rules instead of this convention.
The week number shown for 12 October 2030 counts full weeks from the start of 2030, a figure used in payroll cycles, rostering and any planning done in weekly or fortnightly blocks rather than by calendar month. Businesses running fortnightly pay runs rely on this figure to track which of the two alternating pay weeks a date falls in.