The identical input options criterion requires that all voters have the same set of options for casting their ballot. If there exists some voter who can cast a vote that another voter cannot cast, then this criterion is not met.
More formally, a voting method passes the identical input options criterion if there exists some set of valid ballots such that a list of ballots is in the domain of if and only if .
The identical input options criterion is implied by the anonymity criterion and by the cancellation criterion.