A general election in the United Kingdom involves eligible voters casting their ballots to select their Members of Parliament, i.e. their representatives in the House of Commons, which is the lower house of Parliament. Following the dissolution of the previous parliament, all seats are contested at the same time using the first past the post voting system. The country is divided into several hundred regions called constituencies; one constituency elects one MP, with the candidate achieving the most votes winning the seat whether they have a majority of votes or not. The legal maximum lifetime of a Parliament is five years, but in practice it is nearly always dissolved earlier by Royal Proclamation. The political party that wins the most seats usually forms the next government, with its leader the prime minister. The party in opposition to the government, which is usually the second-largest party, is known as the 'Official Opposition'.
The next general election is scheduled to take place in 2022.
Parties in Northern Ireland do not contest seats in Great Britain and are unchallenged by or stand under electoral pacts with parties in the rest of the UK.
Eligibility to vote in and stand for election in UK general elections is not restricted to British citizens; Irish citizens and those of Commonwealth of Nations countries can also participate, though European Union citizens cannot. Voters must be over the age of 18 and not in prison, suffering from a certain level of poor mental health, or guilty of serious electoral malpractice. at the time of the election. Voting is also denied to members of the House of Lords. Voters are disenfranchised if their names do not appear on annually-updated local electoral registers; the Electoral Commission estimates there are about six or seven million people with a theoretical right to vote who cannot exercise it because they are not on the register.
On polling day, usually a Thursday, voters may journey to a local polling station to cast a secret ballot; this usually involves marking a cross next to a single candidate's name on a slip of paper, which is then folded and placed in a secure ballot box. Voting is also possible by post or by proxy (when someone else is nominated to vote on the constituent's behalf). UK voters may also vote by post from abroad.
The election closes at 10pm, when the media usually produce exit polls predicting the overall winner based on responses from a representative sample of voters. The wait for a winning party to emerge traditionally goes on into the small hours of the next day, as the majority of constituencies start counting votes immediately. Once a returning officer in a constituency is a satisfied that a fair ballot has taken place, the results are announced, with candidates appearing on a stage and their names and number of votes read aloud in alphabetical order. Another tradition amongst some constituencies involves a race to declare first; however, any recount in a close contest can push back the result to well into daylight hours. In the case of a dead heat, the seat is decided by drawing lots, though this has never happened since the introduction of universal suffrage (it is, however, not uncommon in local council elections, where the number of votes is much smaller).
Once the result is known, any change of government usually occurs on the same day. The outgoing prime minister meets the monarch in order to resign along with the whole government, and soon afterwards the leader of the largest party meets the sovereign to take on the role, in a ceremony often referred to as "kissing hands". The position of Opposition Leader is occupied immediately and without ceremony by the leader of the second-largest party, so if the two largest parties have swapped places, the previous prime minister automatically becomes the Leader of the Opposition. If the prime minister's party has won the election, the leader must still seek an audience with the monarch in order to renew the office.