The short answer

Formal and informal votes explained

A formal vote is a ballot paper that has been completed in accordance with the Commonwealth Electoral Act 1918 and the instructions on the ballot paper. It clearly indicates the voter's preferences in the required manner and can be admitted to the count. An informal vote fails one or more of these requirements and is set aside during the count — even if an observer or polling official thinks the voter's general intention was obvious. The distinction is critical because informal votes are excluded from the final tally and effectively do not count towards any candidate or party.

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 makes a House of Representatives ballot formal

For the House of Representatives, a formal ballot paper must have the number 1 placed in the box next to one candidate, and a consecutive sequence of numbers — 2, 3, 4 and so on — placed in the boxes next to every other candidate on the ballot paper. Every box must contain a number, and the sequence must be unbroken. If you leave a box blank, repeat a number, or skip a number in the sequence, your vote is informal.

The full preferential system used for the House of Representatives means that a voter must express a preference for every candidate, not just their first choice. There is no option to select only one candidate or to stop numbering partway through. Even if you number every box but use a tick, a cross, or a symbol instead of a number anywhere, your ballot is informal — the AEC requires numbers only.

Evidence review

What makes a Senate ballot formal

Senate ballot papers offer two ways to cast a formal vote. You can vote above the line by numbering at least six boxes for parties or groups in order of your preference — 1, 2, 3, 4, 5 and 6. You may continue numbering more boxes if you wish, but six is the minimum. Alternatively, you can complete the ballot below the line by numbering at least 12 boxes for individual candidates in order of your preference.

If you mix the two methods — for example, numbering some above-the-line boxes and some below-the-line boxes — the ballot is informal. The instructions on the Senate ballot paper explain this clearly. The introduction of optional preferential voting above the line and partial preferential voting below the line in 2016 reduced the Senate informality rate compared with the earlier full-preferential system, which required numbering every box.

Evidence review

Common causes of informal voting

The most common causes of informal voting include leaving the ballot paper blank, numbering only one box (for the House of Representatives), using ticks or crosses instead of numbers, repeating a number, omitting a number in the sequence, writing comments or slogans on the ballot paper, or the ballot paper being torn or its identifying marks removed. Scribbling, drawing pictures or writing a candidate's name across the paper also makes the ballot informal.

A ballot paper that has been marked in a way that could identify the voter — for example, signing your name on the paper — is also informal. This rule exists to protect the secrecy of the ballot. The ballot paper itself must not be traceable to the individual voter. Even a stray mark that could serve as an identifier may cause the paper to be set aside.

Evidence review

The saving provision: when an informal-looking vote may still count

There is a narrow legal provision that can save a vote from informality. Section 268 of the Commonwealth Electoral Act allows a ballot paper to be counted as formal if the voter has clearly indicated a preference for one candidate over all others, and the paper does not contain any other identifying mark that would breach the secrecy of the ballot. This provision is interpreted conservatively by the Australian Electoral Officer and scrutineers at the count.

In practice, this saving provision mainly applies to House of Representatives ballots where the voter has numbered 1 next to a candidate and left all other boxes blank — in that case, the voter's clear first preference may be admitted. It does not apply to Senate ballots, which require minimum numbers of preferences. Do not rely on the saving provision; always follow the ballot paper instructions.

Evidence review

How informal votes affect election results

Informal votes are tallied separately and reported as a percentage of total votes cast, but they do not affect the distribution of preferences or the determination of the winner. In a close contest, a high informal vote can attract political attention because it reduces the pool of formal votes needed for a candidate to reach the required majority. In the House of Representatives, a candidate must receive more than 50 per cent of the formal two-candidate-preferred vote to win — informal votes are excluded from both the numerator and the denominator.

Historically, the national informality rate for House of Representatives elections in Australia has ranged between approximately 3 and 6 per cent. Senate informality rates are usually lower because optional preferential voting above the line simplifies the process. Higher informality rates are sometimes observed in divisions with large numbers of candidates, in areas with higher proportions of voters from non-English-speaking backgrounds, or where ballot paper instructions have changed.

Evidence review

What to do if you make a mistake on your ballot paper

If you realise you have made a mistake before placing your ballot paper in the ballot box, you can return the spoiled ballot paper to a polling official and request a replacement. The spoiled paper is cancelled and you receive a fresh ballot. You are entitled to one replacement ballot paper. If you make a second mistake, you should still complete the paper as best you can and place it in the box rather than leaving it blank.

Once the ballot paper is in the ballot box, it cannot be retrieved or changed. There is no process for correcting a ballot after it has been cast. This is why it is important to read the instructions on the ballot paper carefully and ask a polling official for help if you are unsure — they can explain the requirements without influencing your choices.

Common questions

Before you rely on the answer

If I number 1 for my preferred candidate and leave the rest blank, does my vote count?

For the House of Representatives, this is technically informal because you have not completed a full preferential sequence. However, under a saving provision the ballot may still be admitted if your first preference is unambiguous. This is not guaranteed and you should not rely on it. For the Senate, leaving boxes blank beyond the minimum required 6 above the line or 12 below the line is allowed, but numbering fewer than the minimum makes the vote informal.

What is the informality rate typically like in Australian federal elections?

The informality rate for the House of Representatives has historically been between 3 and 6 per cent of total votes cast. The Senate informality rate is typically lower, often around 3 per cent or less, reflecting the simpler above-the-line voting option. These rates can vary between divisions and states.

Does a stray pen mark automatically make my vote informal?

Not necessarily. A stray mark that is clearly accidental and does not identify the voter is generally ignored. However, if the mark could reasonably be interpreted as an identifier — for example, a signature or a distinctive symbol — the vote will be set aside as informal. The counting officer and scrutineers make this determination during the count.

Can I use a pen that is not the one provided at the polling place?

Yes, you may use your own pen. However, the AEC recommends using the pencil provided at polling places because pencils are reliable, cannot run out of ink and do not smudge. A ballot marked in ink that bleeds through the paper or obscures your numbering may be challenged as informal.

Source spine

Primary material used for this guide

Review trigger: Review when the Commonwealth Electoral Act 1918 is amended, when AEC ballot paper instructions change, or when the formality saving provision under section 268 is modified by legislation.

Archive note: Based on AEC counting and voting guidance and the Commonwealth Electoral Act 1918 as at July 2026. Ballot paper formality rules are set by legislation and can change between elections. Always check the current instructions on your ballot paper when voting.

Primary links are provided without affiliate or tracking parameters. Confirm that the source still applies to the bill, sitting date, jurisdiction or reporting period before relying on it.