Voting Systems in Australia

Previous pages introduced voting systems in context. This page provides more detail - explaining preferential voting, proportional representation, and Hare-Clark with explanations and worked examples.

Australia’s electoral systems were designed to do more than simply identify the candidate with the most votes. In many cases, they aim to ensure that the winner has majority support, or that a parliament more fairly reflects the diversity of views in the electorate.

How to use this guide

This page explains the main voting systems used across Australian elections and where they apply. By the end, you should be able to understand the basics of any Australian ballot paper.

1. Overview  ·  2. Federal Government  ·  3. States & Territories  ·  4. Local Government  ·  5. Voting Systems

Why does Australia use preferential voting?

In many countries, elections use a simple "first-past-the-post" system: the candidate with the most votes wins, even if they do not have majority support. Australia’s preferential systems were designed to reduce that problem by asking voters to rank candidates instead of choosing only one.

There are three main systems used across Australian elections:

• Full preferential voting — used for the federal House of Representatives and several state lower houses
• Optional preferential voting — used in New South Wales and Queensland lower-house and some local elections
• Proportional representation — used for the Senate and most state upper houses

Tasmania and the ACT also use a distinctive system called Hare-Clark, which is a proportional system with multi-member electorates and ranked voting.

Where it is used

Federal House of Representatives, Victoria lower house, South Australia lower house, Western Australia lower house, Northern Territory lower house, and many local councils.

How it works

You must number every box on the ballot paper, ranking all candidates from 1 for your most preferred candidate through to the final number for your least preferred. Leaving boxes blank usually makes the ballot informal.

If a candidate gets more than 50% of first-preference votes, they win immediately. If not, the candidate with the fewest votes is eliminated, and their votes are redistributed according to the next preferences marked on each ballot. This continues until one candidate has a majority.

Worked example

Imagine an electorate with 1,000 voters and four candidates. First preferences are counted:

Round 1: Nobody has a majority, so Dave is eliminated. His votes are redistributed according to second preferences. Round 2: Carol becomes the lowest remaining candidate and is eliminated. Her votes then redistribute. Round 3: Alice reaches 520 and wins with a majority.

Where it is used

New South Wales lower house, Queensland lower house, and some local government elections.

How it works

Optional preferential voting is similar to full preferential voting, except that you do not have to rank every candidate. You must number at least one box, but you may choose to number only some of the candidates.

The trade-off

The system is simpler for some voters because it does not force a full ranking. But it also means ballots can become exhausted. If all the candidates you ranked are eliminated, your ballot takes no further part in the count.

This means the final winner may have a majority of the remaining active votes, but not necessarily a majority of all votes originally cast.

Where it is used

Typically in the parliamentary upper houses; Federal Senate, New South Wales Legislative Council, Victorian Legislative Council, South Australian Legislative Council, and Western Australian Legislative Council.

The problem it solves

Single-member electorates often favour major parties. A party with 15% of the vote nationwide may win very few seats if it consistently comes third or fourth in individual electorates. Proportional systems are designed to translate vote share into representation more fairly.

The quota

To win a seat, a candidate or party must reach a quota - a mathematical threshold based on the number of votes cast and the number of seats available.

In a half-Senate election, where six senators are elected in a state, the quota is roughly one-seventh of the total valid vote plus one. That usually means a party needs about 14.3% of the vote to win a seat.

Above the line and below the line

Senate ballot papers allow two broad ways to vote. "Above the line", where voters rank parties. "Below the line", where voters rank individual candidates. Below-the-line voting gives more control over the choice of candidates, including within parties.

Surplus votes and preferences

When a candidate receives more than a quota, their surplus votes are redistributed according to next preferences. Candidates with too few votes are eliminated and their votes are redistributed. The process continues until all seats are filled.

Where it is used

Tasmania House of Assembly, ACT Legislative Assembly, and most Tasmanian local councils.

What is Hare-Clark?

Hare-Clark is a form of proportional representation that uses multi-member electorates and ranked voting. Rather than dividing a state or territory into many single-member seats, it uses larger electorates that each elect several members.

In Tasmania, five electorates each elect seven members. In the ACT, multiple electorates each elect several members.

Key features

• Ranked voting: voters rank candidates in order of preference
• Proportional quota: candidates are elected once they reach a quota
• No above-the-line shortcut is available: voters choose individual candidates directly
• Robson rotation: candidate order changes between ballot paper versions to reduce the "donkey vote" effect

Why it matters

Because several members are elected from each electorate, minor parties and independents need only a share of the vote rather than an outright majority. This tends to produce more diverse and more proportionally representative parliaments.

Australia is one of the relatively few democracies where voting is compulsory. At the federal level and in most state elections, enrolled citizens must vote or face a fine.

Technically, the obligation is to attend or otherwise cast a valid participation attempt, such as returning a postal vote. You cannot be forced to complete the ballot correctly, which is why informal votes still occur.

Local government voting is not compulsory in every jurisdiction. South Australia, Western Australia, the Northern Territory, and Tasmania do not generally require voting in local council elections.

Before you can vote in any Australian election, you must be enrolled on the electoral roll. Enrolment is compulsory for Australian citizens aged 18 and over, and your details must be kept up to date if you move.

For federal elections, enrolment is managed by the Australian Electoral Commission. States and territories also have their own electoral bodies for state and many local elections.

Rolls close shortly before elections, so keeping your enrolment current is important.