Countback

Unlike other methods of filling vacancies, this procedure maintains proportional representation, and eliminates the need for expensive and low-turnout special elections.

However, the procedure for this can quickly become complex and highly arbitrary, with the outcome depending strongly on minor variants in counting rules (e.g. which candidates are considered "eliminated" in each round).

This procedure also inserts spoiler effects into the race, allowing the final result to depend on the order in which vacancies arise, and potentially excluding popular candidates from contention because they were eliminated in early rounds.

In 1985 the Tasmanian Parliament amended the Electoral Act to allow true by-elections if no candidates of the same party as the outgoing representative remained on the ballot.

However, this has not happened because most political parties and community groups now nominate a surplus number of candidates, in order to ensure they can fill any casual vacancies.