King's Birthday falls on the second Monday of June in New South Wales, Victoria, South Australia, Tasmania, the Northern Territory and the ACT. Western Australia and Queensland do not observe the holiday on this date, so 11 June 2028 carries the public holiday in six jurisdictions and not in the other two, one of the clearest state-by-state splits on the calendar.
Retail, hospitality, healthcare and emergency services rosters regularly schedule staff to work on Sundays as part of standard shift patterns that do not follow the Monday-to-Friday week. 11 June 2028 falls on Sunday, a working day for these shift-based industries even though it sits outside the standard working-day count above.
The quarter containing 11 June 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.