The Australian Electoral Commission (AEC), an independent statutory authority, oversees the apportionment and redistribution process for federal divisions, taking into account a number of factors.
[1] Politicians, political parties and the public may make submissions to the AEC on proposed new boundaries, but any interference with their deliberations is considered a serious offence.
Each state and territory has its own commission which follows similar but not identical processes and principles for determining electoral boundaries and conducting elections within their jurisdiction, and those of local governments.
Within the following 30 days, the Electoral Commission made a judgement that there was possibility of a change in seat entitlement for ACT.
[10] The redistributions and boundaries for New South Wales, Victoria and Western Australia had just recently been finalised within the month prior.
Under Section 59 of the Commonwealth Electoral Act, if the number of electors in more than one third of the divisions in a State or one of the divisions in a Territory deviates from the respective State/Territory's average divisional enrolment by more than 10% for a period of more than two months, this is considered malapportionment and is one of the three possible triggers for redistribution for that State or Territory.
High Court rulings have later interpreted this section of the Constitution to apply to state members and senators.
However, each Original State is entitled to a minimum of five members under the Australian Constitution, thus giving Tasmania two more seats than its population would normally justify.
The quotient and the error margin were added and rounded to the nearest whole number to determine the entitlement for each territory.
Following its timeline, the AEC on 27 July 2023 announced an apportionment determination based on the population figures for December 2022.
[19] The number of seats by States in the House of Representatives arising from the 2020 determination, with the change in law relating to the territories, were as follows: The population quota is 173,647 (25,005,200 divided by 144).
[16] The number of seats by States in the House of Representatives arising from the 2014 determination were as follows:[33] A redistribution of electoral boundaries in New South Wales and Western Australia was undertaken before the 2016 election.
[33] The redistribution in New South Wales was announced on 16 October 2015, with the Labor-held Division of Hunter proposed to be abolished.
[35] A redistribution also occurred in the Australian Capital Territory, as seven years had elapsed since the last time the ACT's boundaries were reviewed.
However, under Section 59 of the Commonwealth Electoral Act 1918, as the date will fall within the last 12 months of the 47th Parliament (due to expire 25 July 2025), the redistribution will be deferred to after the 2025 election.
This was the third time South Australia lost a seat since the 1984 enlargement of the parliament, with Hawker abolished in 1993 and Bonython in 2004.
However, under Section 59 of the Commonwealth Electoral Act 1918, as the date fell within the last 12 months of the 47th Parliament (due to expire 25 July 2025), the redistribution was deferred to after the 2025 election.
[58] A redistribution of federal election divisions in Western Australia was undertaken in 2020, due to changes in the state's representation entitlement.
Due to changes in the state's representation entitlement, Western Australia gained a seat in the 2024 redistribution.
[60] A redistribution of federal electoral divisions in Victoria commenced on 4 September 2017, due to changes in the state's representation entitlement.
The determinations were made on 13 July 2018, and created a 38th electoral division named Fraser (notionally a safe Labor).
[61] Several divisions were also renamed: Batman to Cooper (after William Cooper), McMillan to Monash (after Sir John Monash), Melbourne Ports to Macnamara (after Dame Jean Macnamara) and Murray to Nicholls (after Sir Douglas and Lady Nicholls).
Politicians have no influence over the process, although they, along with any other citizen or organisation, can make submissions to the independent authorities suggesting changes.
The Playmander distorted electoral boundaries and policies that kept the Liberal and Country League in power for 32 years from 1936 to 1968.
Supporters of such arrangements claimed Australia's urban population dominates the countryside and that these practices gave fair representation to country people.
Most divisions are named in honour of prominent historical people, such as former politicians (often Prime Ministers), explorers, artists and engineers, and rarely for geographic places.
However, in 2024, the namesake was altered to be joint between both men, to give recognition to Joseph Cook and have a division named after him.
For example, the Bennelong (the seat John Howard held as Prime Minister) and Warringah (the seat Tony Abbott held as Prime Minister) will not be renamed "Howard" and "Abbott", respectively due to these names being Indigenous, while Wentworth (the seat Malcolm Turnbull held as Prime Minister) will not be renamed "Turnbull" due to Wentworth being one of the 34 remaining original divisions created.
Thus, the following divisions share the same name as a state electoral district (Tasmanian electorates share the same names on both levels of politics and are thus not included as pairs of examples): After a redistribution is carried out in a state or territory, the AEC calculates "notional" margins for the redistributed divisions by modelling the outcome of the previous election as if the new boundaries had been in place.
These notional margins are used as the baseline for the electoral swings calculated and published in the AEC's virtual tally room at the following election.