The formal end of a Parliament is called dissolution. Parliament is dissolved automatically 25 working days before a general election. The Fixed-Term Parliaments Act 2011 provides that general elections take place every five years on the first Thursday in May.
It also provides for early general elections if
• either, the House agrees a motion that there should be an early general election (which, if decided on a division, requires the support of two-thirds of the House’s total membership),
• or, the House fails to agree a vote of confidence in a new Government within 14 days of a vote of no confidence in the Government holding office
Parliament is normally prorogued a few days before dissolution takes place. At prorogation, all parliamentary business ends but Parliament continues to exist until dissolution.
Dissolution triggers the start of the general election campaign. It also begins the period of ‘purdah’: the convention that the Government doesn’t make major policy announcements or enter into significant commitments during the run up to an election.
When Parliament is dissolved, every seat in the House of Commons becomes vacant. You’re no longer an MP and mustn’t use this title. The House and IPSA issue detailed guidance before dissolution for MPs and their staff. The facilities that the House provides are no longer available to you from 5pm on the day of dissolution.
Before the Fixed-Term Parliaments Act, the decision to bring a Parliament to an end and hold a general election held lay in the hands of the Prime Minister, who was able to advise the Queen to exercise the prerogative power to dissolve Parliament.