What is an informal vote in an Australian election?

An informal vote in an Australian election is a ballot paper that does not comply with the formal voting rules and is therefore not counted toward any candidate. Informal votes are recorded by the Australian Electoral Commission (AEC) and reported in the official results but do not affect the outcome of the election.

Several common causes produce informal votes. Leaving any box blank on a House of Representatives ballot (where full preferential voting requires every box to be numbered) is the most common cause. Numbering only one or some boxes is informal at federal level. Skipping numbers (numbering 1, 2, 4, 5 but leaving 3 blank) is informal. Repeating numbers (numbering two boxes both as 2) is informal. Writing names, messages, or symbols is informal. Marking the ballot in ways that don't constitute proper preferences (such as ticks or crosses everywhere) is informal. Identifying the voter by writing their name on the ballot is informal.

Some apparent informalities are saved by the Commonwealth Electoral Act. A single tick or cross used as the number 1 is generally accepted. Some minor mistakes can be saved if the voter's intention is clear (the so-called 'savings provisions'). The AEC interprets ballots generously where possible, subject to the technical rules.

Informal voting rates vary. The House of Representatives informal vote at federal elections has ranged from about 4 to 7 per cent in recent decades, sitting at 5.18 per cent at the 2022 federal election. The Senate informal vote is typically lower (around 4 per cent) because of the easier above-the-line voting option that requires only six numbers. Informal rates are higher in electorates with large non-English-speaking populations, suggesting language difficulties contribute. The AEC runs extensive multilingual voter education campaigns before each election to reduce unintended informality. Optional preferential voting (used in some state lower houses) reduces informal rates by accepting partial preferences, but the federal House continues to require full preferential voting to keep clear majoritarian outcomes.