Spoilt vote

In voting, a ballot is considered to be spoilt, void, null or informal if it is regarded by the election authorities to be invalid and thus not included in the tally during vote counting. This may be done accidentally or deliberately.

Ways of spoiling a ballot include:

• leaving the ballot blank (though some ballots include an explicit "none of the above" option)
• completing the ballot in an illogical or unapproved manner, such as:
  • voting for more than one candidate in a plurality voting system
  • voting for too many or too few candidates in any system where such limits are specified
  • filling a preference ballot out of sequence, e.g 1-2-2-3-4 or 1-2-4-5-6, or marking such a ballot with an "X"
• filling the ballot in a manner which is illegible or incomprehensible
• physically deforming ballots, especially those counted by machine
• writing on the ballot, other than the minimal marks necessary to complete it, may be regarded as compromising the secrecy of the ballot due to the possibility of handwriting analysis establishing the voter's identity

Ballot design and voter instruction are intended to minimise accidental spoiling of votes. Some election officials have discretion to include ballots where the strict criteria for acceptability are not met but the voter's intention is clear. More complicated electoral systems may be more prone to errors. Group voting tickets were introduced in Australia owing to the high number of informal votes cast in single transferable vote elections.

Spoilt votes may be the result of a deliberate act by the voter; some proportion are likely to be protest votes, especially in systems where voting is compulsory. Intentionally spoiling someone else's ballot before or any ballot during tabulation is a method of election fraud. In Australia, inciting others to vote informally is illegal, though informal voting is not.

Paper-based voting systems are thought to be more susceptible to unintentional errors that spoil ballots; some paper-based voting systems and most DRE voting machines can notify voters of undervotes and overvotes.

The validity of the election may be questioned if there is an unusually high proportion of spoilt votes, however, in countries such as the UK where a spoilt ballot paper counts towards the voter turnout, some voters will deliberately spoil their ballot paper to show disapproval of the candidates available whilst still taking part in the electoral process. In theory, a UK election could have a 100% turnout with no votes cast for any of the candidates if every registered voter were to spoil their paper although this is highly improbable.

See also

• Election fraud
• Ballot design in the Single Transferable Vote: discusses exhausted votes, which cannot be transferred owing to too few preferences being expressed