An overvote occurs when one votes for more than the maximum number of selections allowed in a contest.^[1] The result is a spoiled vote which is not included in the final tally.

One example of an overvote would be voting for two candidates in a single race with the instruction "Vote for not more than one." Robert's Rules of Order notes that such votes are illegal.^[2]

The exact definition of overvotes is ambiguous in a contest with N-of-M voting, where N of M choices can be selected and N>1 (vote for no more than N). Sometimes overvotes are reported as the number of ballots overvoted in the contest, and sometimes it is reported as N*overvoted-ballots.

Undervotes combined with overvotes (known as residual votes) can be an academic indicator in evaluating the accuracy of a voting system when recording voter intent.^[3]

While an overvote in a plurality voting system or limited voting is always illegal, in certain other electoral methods including approval voting, this style of voting is valid, and thus invalid overvotes are not possible.^[4]

In the corporate world, the term "overvote" describes a situation in which someone votes more proxies than they are authorized to, or for more shares than they hold of record.^[5]