Federal elections

Australia is a representative democracy, which means Australians vote to elect members of parliament to make laws and decisions on their behalf. It is compulsory for Australian citizens 18 years and over to enrol to vote. It is also compulsory to attend a voting place on election day or to vote by mail.

At federal elections, Australians choose members of parliament to represent their views and interests in the Senate and the House of Representatives. In this way, the Australian Parliament serves Australians and is accountable to them.

Electing members of the House of Representatives

Section 28 of the Australian Constitution states that House of Representatives elections must be held at least every 3 years. The Prime Minister decides the date for an election. This could be at any time during the 3-year term.

There are 151 members elected to the House of Representatives—one for each of Australia's 151 electorates. There is approximately the same number of voters in each electorate.

Each member is elected using a system of preferential voting, designed to elect a single member with an absolute majority – more than half – for each electorate. Using this system, voters write a number in the box beside every name on the ballot-paper: '1' for their first preference, '2' for their second preference and so on, until all the boxes are numbered. If a candidate gains an absolute majority of first preference votes, they win the seat. If no candidate receives an absolute majority, the candidate with the least number of votes is excluded and their votes are redistributed according to second preferences. The process of redistributing votes according to preferences continues until one candidate receives more than 50 per cent of the vote and is then elected.

Electing senators

Twelve senators are elected to represent each state and 2 senators are elected to represent each territory. State senators are elected for a period of 6 years using a system of rotation that ensures that only half the state senators end their term every 3 years. Territory senators are elected for a period of 3 years at the same time as the members of the House of Representatives and half of the Senate.

Half-Senate elections are usually held at the same time as House of Representatives elections, though they do not have to be.

Senators are elected by a preferential voting system—proportional voting—which is designed to allocate seats to candidates in proportion to votes cast in an election. A wider range of political parties and/or independents are often elected to the Senate.

Voters have a choice of voting above-the-line or below-the-line:

• Above-the-line voting requires voters to number at least 6 boxes from 1 to 6 for their chosen parties or groups. Voters' preferences are distributed in the order that the candidates in the chosen parties or groups are listed below the line. Preferences are distributed to the party or group of first choice, then second choice and so on, until all preferences are distributed.
• Below-the-line voting requires voters to number at least 12 boxes from 1 to 12 for their chosen individual candidates. Voters' preferences are distributed to the candidates in the order of choice, as numbered on the ballot paper.

To win a seat, a senator must gain a quota of first and later preferences. For a state senator at a half-Senate election, this equals 14.3% of the total state vote, while a territory senator must win 33.3% of the total territory vote.

The counting procedure for a Senate election is more complicated than the system used for the House of Representatives—it sometimes takes several weeks after an election to count all the Senate votes and finalise the result.

Finalising the result

Once the election result is finalised, the successful candidates are declared and the writs are returned to the Governor-General for the House of Representatives and state governors for the Senate.

By-elections and casual vacancies

A by-election is a mini-election held for a House of Representatives electorate if a member resigns, becomes ineligible or dies between federal elections.

A casual vacancy occurs in the Senate if a senator resigns, becomes ineligible or dies between federal elections. They are replaced by a candidate from the same political party, chosen by the parliament or legislative assembly of that state/territory.

Legal requirements

Federal elections are organised and run by the Australian Electoral Commission, who make sure that elections are free, fair and legal. The Commonwealth Electoral Act 1918 and the Australian Constitution set out the requirements for running elections.