A redistribution is a redrawing of electoral boundaries.

For the House of Representatives each State and Territory is divided into electoral divisions. The number of these divisions is determined by population. To ensure equal representation, the boundaries of these divisions have to be redrawn or redistributed periodically.

In deciding where the boundaries should be drawn, many factors are taken into consideration.

A redistribution seeks to ensure that, as nearly as practicable, there are an equal number of electors in each electoral division for a given state or territory. Electoral boundaries are redrawn (or redistributed) with the aim that in three years and six months after the completion of the redistribution the number of electors in each division in a State or Territory will vary by no more than 3.5% from the average divisional enrolment for that State or Territory.

A redistribution is required when:

- the number of parliamentary representatives to which a state or territory is entitled changes (population change);
- the number of electors in more than one-third of the divisions in a State (or one of the divisions in the ACT or Northern Territory) deviates from the average divisional enrolment by over ten per cent for more than two months; or
- seven years has elapsed since the last redistribution.

Twelve months after the first meeting of the newly elected House of Representatives, the Electoral Commissioner ascertains the population of the Commonwealth (excluding the territories) using the latest official statistics published by the Australian Statistician. The Commissioner then makes a determination of the number of parliamentary representatives to which each state is entitled. A similar exercise is used to calculate the entitlements of the territories.

A redistribution is necessary when:

- the number of members in the House of Representatives to which a State or Territory is entitled has changed (see population quota)
- the number of electors in more than one third of the divisions in a State or one of the divisions in the ACT or Northern Territory deviates from the average divisional enrolment by over 10% for a period of more than two months
- a period of seven years has elapsed since the previous redistribution.

A redistribution is undertaken by a committee consisting of the Electoral Commissioner, the Australian Electoral Officer for the State concerned (in the ACT, the senior Divisional Returning Officer), the State Surveyor-General and the State Auditor-General.

As soon as possible after the redistribution process commences, the Electoral Commissioner invites public suggestions on the redistribution which must be lodged within 30 days. A further period of 14 days is allowed for comments on the suggestions lodged.

The Redistribution Committee then divides the State or Territory into divisions and publishes its proposed redistribution.

A period of 28 days is allowed after publication of the proposed redistribution for written objections. A further period of 14 days is provided for comments on the objections lodged. These objections are considered by an augmented Electoral Commission consisting of the four members of the Redistribution Committee and the two part-time members of the Electoral Commission.

At the time of the redistribution the number of electors in the divisions may vary up to 10% from the 'quota' or average divisional figure, and at the projection time, usually 3.5 years after the expected completion of the redistribution, the figures should not vary from the average projected quota by more or less than 3.5%. The augmented Electoral Commission publishes its decision and reasons in a report.

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

The term 'quota' is used in two contexts in the redistribution process.

This term is used when calculating the number of House of Representatives members a State or Territory is entitled to (i.e. the number of divisions).

During the thirteenth month after the first meeting of the newly elected House of Representatives, the Electoral Commissioner is required to ascertain the population of the Commonwealth (excluding the Territories) according to the latest official statistics available from the Australian Statistician. These figures are then used to determine how many members of the House of Representatives (divisions) each State is entitled to.

A similar exercise is used to calculate the entitlements of the Territories.

The determination of Representation entitlements at 29 September 2011.

The calculation is as follows:

**Total population of the six States / (2 x number of Senators for the States) = Quota**

The population of the six States divided by twice the number of Senators for the States.

**21 883 246 / (72 x 2) = 151 966.9861** (as at 29 September 2011)

**Total population of individual State or Territory ^{1} / Quota = Number of members**

State | Population | Quota | Entitlement | Divisions |
---|---|---|---|---|

New South Wales | 7 272 230 | 151 966.9861 | 47.8540 | 48 |

Victoria | 5 585 573 | 36.7552 | 37 | |

Queensland | 4 548 700 | 29.9322 | 30 | |

Western Australia | 2 317 068 | 15.2472 | 15 | |

South Australia | 1 650 383 | 10.8601 | 11 | |

Tasmania | 509 292 | 3.3513 | 5* | |

ACT^{2} |
362 424 | 2.3849 | 2 | |

NT^{3} |
231 953 | 1.5263 | 2 | |

Total | 150 |

* The Constitution (s.24) grants Tasmania a minimum of five members in the House of Representatives.

Note: In calculating step two, if the remainder is more than 0.5, the figure for the number of members is rounded up. If the remainder is less than or equal to 0.5, the figure is rounded down (i.e. 2.5 = 2 members, and 2.52 = 3 members).

- Under Section 38A of the Electoral Act, the Territory of Norfolk Island is not taken to be a Territory for this determination, but defined Norfolk Islanders are included in the population figures.
- The population figure for the Australian Capital Territory includes Jervis Bay.
- The population figure for the Northern Territory includes Cocos (Keeling) Islands and Christmas Island.

There are two enrolment quotas calculated during the redistribution process:

- the current quota or average divisional enrolment; and
- the projected quota or average divisional enrolment at the projection time, which is usually three and half years after the expected completion of the redistribution.

In each case, the quota is calculated by dividing the number of people enrolled by the number of members to which the State or Territory is entitled.

The current quota uses the number of electors on the roll when the redistribution commences and is permitted to vary by up to 10% in each division. The projected quota, on the other hand, is based on a projected enrolment figure, usually three and a half years after the expected completion of the redistribution, and may vary by no more than 3.5% in each division.

*For example, the quota in NSW was calculated at the beginning of the 2009 redistribution process as follows:*

**Number of electors enrolled in NSW (4 528 940) / Number of divisions into which NSW is to be distributed (48) = 94 353**

Therefore at the time of the redistribution the number of electors in the divisions could vary up to 10% from 94 353, i.e. the permissible maximum (+10%) would be 103 788 and the permissible minimum (- 10%) would be 84 918.

*The projected quota for NSW was calculated as follows:*

**Projected enrolment in NSW at 16.07.12 (4 747 516) / Number of members NSW is entitled to (48) = 98 907**

Therefore, the quota, or projected average enrolment at July 2012 (i.e. in three and a half years time) was 98 907 electors for each division in NSW. Enrolments should not vary from this by more or less than 3.5% (i.e. 103.5% = 102 369 or 96.5% = 95 445).