What is a redistribution?

A federal redistribution is when the boundaries and names of federal electorates are reviewed.

Redistributions are run independently from Government and Parliament. The Australian Electoral Commission (AEC) administers the process, but an independent committee makes the decisions.

Why redistributions happen

As the population grows or shifts, redistributions ensure that:

  • each electorate has roughly the same number of voters, and
  • federal representation across each state or territory remains fair and balanced.

This process helps keep Australia’s electoral system up to date with population changes.

When do redistributions happen?

There are three trigger scenarios below. One of these occurring means a redistribution has to commence.

  1. When the entitlement of a state or territory changes
  2. When electorates contain unequal population
  3. When a redistribution has not been held for seven years.

State and Territory entitlement

Each state and territory is made up of electorates (or seats) for the House of Representatives. The total number of electorates across the country is determined by population. Currently there are 150 electorates, although this can change depending on population distribution.

The representation entitlement for all states and territories is determined by applying the total populations of the states and territories to a particular formula specified in the Commonwealth Electoral Act (section 48). This determines each state and territory’s electorate entitlement. The electorate entitlement means voters are able to be represented by one Member of Parliament standing for each electorate in the House of Representatives.

The Electoral Commissioner ascertains the populations of the states and territories from the Australian Statistician after the opening of a new Parliament.

Who is on the Redistribution committee?

A Redistribution Committee is appointed for the state or territory in which a redistribution has commenced.

The Redistribution Committee consists of the Electoral Commissioner, the Australian Electoral Officer (AEO) for that state or territory (the ACT will use an appointed member of the AEC), the Surveyor-General and the Auditor-General for that state or territory.

The Redistribution Committee is supported by a small secretariat of staff from the Australian Electoral Commission.

Steps in the redistribution process

The redistribution timetable outlines the timing of the legislatively required steps in the redistribution process.


There are two quotas calculated during the redistribution process:

  • the redistribution quota and
  • the projected enrolment quota at the projection time, which is usually three and a half years after the expected completion of the redistribution

Formula to determine redistribution quota

The redistribution quota is determined as soon as practicable after the redistribution commences. It is calculated by dividing the number of electors on the electoral roll in the state or territory on the day the redistribution commences by the number of members to which the state or territory is entitled.

Number of electors enrolled in a state or territory / Number of members the state or territory is entitled to = Redistribution quota

The number of electors in each proposed electorate may vary by up to 10 per cent.

Formula to determine projected enrolment quota

The projected enrolment quota is calculated by dividing the projected number of people enrolled in the state or territory at the projection time by the number of members to which the state or territory is entitled.

Projected enrolment for a state or territory / Number of members the state or territory is entitled to = Projected enrolment quota

As far as practicable, the number of electors in each electorate at the projection time should not vary by 3.5 per cent more or less than the average number of projected electors.

Example of determination of enrolment quotas

The enrolment quotas for South Australia at 12 January 2011 (the commencement date of the redistribution process) were as follows:

Redistribution quota

1 107 001 / 11 = 100 636

The number of electors in each electorate could vary by up to 10 per cent from 100 636. The permissible maximum would be 110 699 and the permissible minimum would be 90 573.

Projected enrolment quota

1 152 271 / 11 = 104 752

The projected average enrolment in each electorate at 21 January 2015 (three and a half years from the date the redistribution was expected to be completed) is 104 752. Enrolments should not vary from this by more or less than 3.5 per cent (i.e. 103.5 per cent = 108 418 or 96.5 per cent = 101 086).

As soon as practicable after the redistribution process commences, the Electoral Commissioner invites interested people or organisations to submit ideas about the redistribution. Public ideas must be lodged within 30 days.

The ideas are made available for public inspection. There is then a period of 14 days in which written feedback on the ideas may be lodged.

Guidelines are available to assist people or organisations interested in submitting ideas.

The Redistribution Committee then divides the state or territory into electorates and publishes its initial proposed redistribution. The Redistribution Committee will take into consideration a number of factors detailed in the Commonwealth Electoral Act 1918 and the public ideas and feedback.

Maps showing the proposed boundaries and names of electorates, together with reasons for the proposed redistribution, are made publicly available by publication on the AEC's website.

There is a period of 28 days within which ideas to the proposed redistribution can be lodged. These initial ideas are made available for public inspection. There is then a period of 14 days in which written feedback on the ideas can be submitted.

Guidelines are available to assist people or organisations interested in submitting ideas.

The augmented Electoral Commission for the state/territory considers ideas to the proposed redistribution. The augmented Electoral Commission comprises of the three members of the Electoral Commission, the AEO for the state/territory (the ACT will use an appointed member of the AEC) and the two state/territory government representatives on the Redistribution Committee.

The augmented Electoral Commission has 60 days after the closing date for receipt of comments on initial ideas to finish its considerations. After considering these ideas, the augmented Electoral Commission publicly announces a proposed redistribution.

If the augmented Electoral Commission's proposed redistribution is significantly different from the proposal made by the Redistribution Committee, the augmented Electoral Commission invites further ideas. Interested people or organisations have seven days to make further feedback.

Having considered any further feedback arising from these ideas, the augmented Electoral Commission will make a final decision of boundaries and names of the electorates in the state or territory.

The augmented Electoral Commission publishes its decision and reasons in a final report which is forwarded to the Special Minister of State and then tabled in both houses of Parliament.

The Parliament has no power to reject or amend the final determination of the augmented Electoral Commission.

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Updated: 16 September 2025