The death of the monarch will usher in many changes, from a new batch of Australian currency to a title change for Australia's leading barristers, but how does Queen Elizabeth II's death affect her birthday public holiday?
The Queen's Birthday public holiday could be renamed, but the dates in each state will likely remain the same.
The name of the holiday is expected to change to The King's Birthday to honour the new monarch, King Charles III, as it was before Queen Elizabeth II took the throne, and a new, one-off holiday has been added to the national calendar to mourn Queen Elizabeth II's death.
Western Australia and Queensland are yet to celebrate the Queen's Birthday holiday this year, so residents could see a name change ahead of the September and October dates.
The public holiday will remain, but the name of the holiday will be discussed shortly with advice from relevant authorities, a Queensland Government spokesperson said.
In Queensland, the birthday of the Sovereign, King or Queen, is observed on the first Monday in October, according to the Qld Holidays Act, 1983.
In Western Australia, the holiday falls on September 26 this year, and all other states celebrate the holiday on the second Monday of June.
The dates in each state will likely remain unchanged, as none reflected the actual date of Queen Elizabeth II's birthday, which was in April.
The monarch's birthday has been celebrated in Australia since 1788, when the King's birthday was first commemorated on June 4, according to an Australian National University essay written by the late historian Ann Moyal.
Australia will also hold a National Day of Mourning on Thursday September 22, and a National Memorial Service will be held at Parliament House, Prime Minister Anthony Albanese said in a statement.
"Queen Elizabeth II is the only reigning monarch most Australians have known and her faithful service will be remembered for centuries to come," Mr Albanese said.
"I encourage all Australians, wherever you may be, to take time to pause and reflect on Her Majesty's extraordinary life of service," he said.
For Victorians, the one-off public holiday will deliver a four-day weekend, as Friday, September 23, is the state's Grand Final Eve public holiday.
The monarch's death has also sparked other changes, including the title of leading barristers changing from Queen's Counsel (QC) to King's Counsel (KC), and new currency with King Charles III's likeness to be rolled out.