How preferential voting works in the House

The short answer

How preferential voting works in the House

Preferential voting in the House of Representatives means voters number every candidate on the ballot paper in order of preference rather than casting a single tick or cross. When votes are counted, a candidate needs more than half of the formal votes to win outright. If no candidate reaches that threshold on the first count, the candidate with the fewest votes is excluded and their ballot papers are redistributed to the voters' next available preferences. This process repeats until one candidate has a majority of the votes remaining in the count. Your vote never becomes wasted simply because your first choice is unpopular; if your first preference is excluded, your ballot continues to count for your next preference at full value. The system is designed so that the winning candidate has demonstrated support from a majority of voters in the electorate, either directly or through the accumulation of preferences.

This guide explains the federal position first. State, territory and local elections can use different rules, dates and ballot systems, so the commission named on your election material is the final operational source.

The useful question is not only “what is the rule?” but also “who administers it, which document controls it, and when might it change?” That distinction prevents an accurate general explanation from becoming wrong advice in a particular election, chamber or policy setting.

Evidence review

What full preferential voting requires on the ballot paper

Under the Commonwealth Electoral Act 1918, a formal House of Representatives vote requires every square on the ballot paper to be numbered consecutively starting from 1. Leaving a square blank, repeating a number, or using ticks or crosses instead of numbers can make the vote informal and exclude it from the count. The AEC provides clear instructions on the ballot paper and at every polling booth explaining that you must write the number 1 in the box next to your first-choice candidate, then number all remaining boxes in order of your preference. The numbering requirement is not optional; it is a legislative requirement that applies in every federal House of Representatives election.

Saving provisions in the Act give some latitude for minor numbering errors, such as an interrupted sequence where the voter's intention remains clear. For example, a ballot numbered 1, 2, 3, 3, 4 may still be counted because the repetition of 3 does not obscure the voter's intended order for the candidates before and after the error. However, ballots with multiple squares left blank or with marks that prevent the AEC from determining a clear preference order will be set aside as informal. The safest approach is to number every box without skipping, repeating or using any mark other than numbers.

Evidence review

How the count proceeds round by round

After polling closes, counting officials sort all formal House ballots into piles according to the first preference marked on each. The first-preference totals are tallied and then compared against the total number of formal votes. A candidate who receives more than 50 per cent of the formal first-preference vote is declared elected immediately. This is called winning on first preferences and typically happens in electorates where a two-party contest is particularly lopsided. In most competitive seats, no candidate reaches 50 per cent outright, and the distribution of preferences begins.

At each round of the count, the candidate with the fewest votes is eliminated. Every ballot that had the eliminated candidate as its current preference is examined, and the vote is transferred to the next available preference that is still in the race. A ballot flows through the count as long as there is a remaining numbered candidate to receive it. If all the candidates a voter numbered have been eliminated, the ballot becomes exhausted and plays no further part in the count. Exhaustion is rare under full preferential voting in the House because voters are required to number every candidate, so there is almost always a surviving candidate to receive each ballot. The process continues until one candidate holds more than half the votes remaining in the count.

Evidence review

The difference between House and Senate preferential systems

Australia uses two distinct preferential voting systems: full preferential in the House of Representatives and proportional representation by single transferable vote in the Senate. In the House, each electorate elects one member and full preferential voting ensures the winner has majority support. In the Senate, each state elects six senators at a regular half-Senate election and the counting system uses quotas rather than a simple majority. The Senate ballot allows voters to vote above the line by numbering at least six party or group boxes, or below the line by numbering at least twelve individual candidates.

This difference matters because some voters confuse the two systems. A House ballot numbered 1 through to all candidates is mandatory and correct. A Senate ballot numbered above the line 1, 2, 3, 4, 5, 6 with no further marks is also valid. The AEC publishes separate how-to-vote guides for each chamber to reduce confusion. Understanding the distinction ensures your vote is formal in both contests and that your preferences are distributed according to the rules of each chamber's electoral system.

Evidence review

Why preferences matter for campaign strategy

Preference flows are central to Australian electoral strategy because the final result in a marginal seat often turns on where the preferences of excluded minor-party and independent candidates go. Political parties negotiate preference deals and issue how-to-vote cards recommending a particular preference order. These recommendations are advisory only; voters are free to ignore them and number candidates in any order they choose. The ballot paper belongs to the voter, not to any party or candidate, and the count follows the numbers on the paper, not any external recommendation.

The AEC does not endorse or enforce party how-to-vote recommendations. Its role is to count the votes as marked by each voter. Media commentary during election night often refers to preference deals and expected preference flows, but these are projections based on historical patterns and party recommendations, not guarantees. Actual preference flows can differ significantly from party recommendations, especially when a local issue or candidate profile causes voters to depart from the party line. The Two-Candidate-Preferred count published by the AEC after each election shows the actual distribution and is the authoritative record of how preferences flowed.

Evidence review

Informal voting and how to avoid it

Informal votes in the House of Representatives do not count toward any candidate. Under the Commonwealth Electoral Act, a ballot is informal if it is blank, has no vote marked, or has markings that fail to indicate a clear order of preference. The most common causes of informality are leaving squares blank, repeating numbers, using ticks or crosses, or writing slogans or identifying marks on the ballot paper. The informal voting rate in House elections has typically ranged between 3 and 6 per cent depending on the electorate, with higher rates in areas where many voters speak English as a second language or where there are many candidates.

To avoid casting an informal vote, read the instructions printed on the ballot paper carefully and follow them exactly. If you make a mistake, you can return the ballot to a polling official and request a replacement before placing it in the ballot box. Once the ballot is in the box it cannot be retrieved or corrected. The AEC provides translated guides and has polling staff available to explain the process without advising you which candidate to preference. If you are unsure about any aspect of marking your ballot, ask a polling official before you place it in the box.

Evidence review

The Two-Candidate-Preferred count as the authoritative result

After the election, the AEC conducts a full distribution of preferences for every House of Representatives electorate and publishes the Two-Candidate-Preferred result. This is the count that shows the final contest between the two remaining candidates after all others have been excluded. The TCP count is the official basis for declaring the winner and is the figure used in electoral analysis, not the first-preference count. Media often reports the Two-Party-Preferred estimate, which allocates preferences to the Coalition and Labor as though they were the final two candidates, but this is a statistical construct rather than a formal electoral result.

The TCP count and the official distribution of preferences are published on the AEC website, usually within weeks of the election for most electorates. Close seats may take longer because they require recounts and the inclusion of declaration and postal votes. The full preference distribution data is publicly available and can be downloaded as a spreadsheet, allowing researchers, journalists and members of the public to examine how preferences flowed between every candidate in the contest. This transparency is an important feature of Australian electoral administration and allows independent verification of the result.

Common questions

Before you rely on the answer