Once the three-year term of the House of Representatives ends or if the House is dissolved earlier, the Governor-General issues writs. Writs are legal documents instructing the Australian Electoral Commission (AEC) to hold elections for the 151 members of the House of Representatives and the four territory senators. State governors issue writs for the election of the state senators.
Once the AEC have counted the votes, the writs are returned which confirms the official results of the election. The writs for the House of Representatives and territory senators are signed by the Australian Electoral Commissioner and returned to the Governor-General.
Writs for the state senators are signed by the electoral officer for each state and returned to the state Governor.
The Australian Constitution states that Parliament must sit within 30 days of the return of the writs. It is up to the Australian Government to decide the date within those 30 days that parliament should open.