The self-lodgement tax deadline falls on 31 October every year, closing the four-month window that opened on 1 July. 5 October 2028 falls inside October, the final month of that window, in the fourth calendar quarter of 2028, with the deadline drawing closer as the month progresses.
Thursday sits one working day ahead of the weekend, making it the point in the week where plans for Friday, Saturday and Sunday commonly get finalised. 5 October 2028 falls on this day of the week, the second-to-last working day before the standard Monday-to-Friday week comes to a close and the weekend takes over.
The quarter containing 5 October 2028 is based on the calendar year running January to December, a separate system from the Australian financial year, which runs from 1 July to 30 June and splits into its own four quarters. Businesses often track both systems side by side, one for tax filings and one for calendar-year planning.