A by-election, also known as a special election in the United States and the Philippines, a bye-election in Ireland, and a bypoll in India, is an election used to fill an office that has become vacant between general elections
. A vacancy may arise as a result of an incumbent dying or resigning, or when the incumbent becomes ineligible to continue in office (because of a recall, a prohibited dual mandate, criminal conviction, or failure to maintain a minimum attendance), or when an election is invalidated by voting irregularities
. By-elections are held in most nations that elect their parliaments through single-member constituencies, whether with or without a runoff round
. In the United Kingdom, a by-election is an election that takes place if a seat in the House of Commons becomes vacant between one General Election and the next
. In New Zealand, a by-election is held to fill a vacant electorate seat, for example, if a member of Parliament resigns or dies
