January sits at the midpoint of the financial year that began on 1 July and runs to 30 June. 5 January 2030 falls in the second half of that financial year, five months out from the EOFY close in June, and inside the first calendar quarter of 2030, which runs from January to March under the standard quarter system used on this page.
A public holiday that falls on a Saturday sits inside the weekend rather than beside it, so it does not automatically create a substitute day off during the working week; whether one applies depends on the specific holiday and the state. Saturday 5 January 2030 falls on this day of the week, inside the weekend itself.
2030 has 365 days on the calendar. Leap years add a single extra day to February, giving those years 366 days instead of 365 and shifting the day-of-year number for every date from March onward by one compared with an ordinary year. This is the only irregularity in the length of the Australian calendar year.