This is the list of United Kingdom MPs by seniority, 2015–2017. The Members of Parliament (MPs) are ranked by the beginning of their terms in office, in the House of Commons. The House of Commons of the 56th Parliament of the United Kingdom was elected on 7 May 2015 and first met on 18 May 2015. Under the Fixed-term Parliaments Act 2011 (as amended) the next general election was scheduled to be on 7 May 2020. An early election or one delayed by up to two months were possible in certain circumstances. In the event an early general election was authorised, by a two-thirds vote of the House of Commons, with the election being arranged for 8 June 2017. The formal dissolution of Parliament takes place twenty-five working days before the polling day to elect the new Parliament.