The Fixed-term Parliaments Act 2011 received Royal Assent on 15 September 2011 and came into force on that day. The Act has a major impact on the timing of parliamentary elections in the UK. It removed the prerogative power of the Queen, on the advice of the Prime Minister, to dissolve Parliament and trigger a general election. The Act set the date of the general election on 7 May 2015 and provided that thereafter general elections are scheduled to take place on the first Thursday in May in every fifth year. The next election was scheduled to take place on 7 May 2020.

However, on 19 April 2017, in accordance with the Act, the House of Commons agreed a motion “That there shall be an early parliamentary general election”. On 18 April 2017, the Prime Minister announced that she planned to call an early election on 8 June 2017. A proclamation, announcing that the general election would take place on 8 June 2017, was issued on 25 April 2017, so Parliament will dissolve on 3 May 2017.

The Act specifies that early elections can be held only:

if a motion for an early general election is agreed either by at least two-thirds of the whole House or without division; or

if a motion of no confidence is passed and no alternative government is confirmed by the Commons within 14 days.

After the election on 8 June, the next general election is scheduled to take place on 5 May 2022.

The Act itself does not affect the operation of parliamentary sessions but from the spring of 2012, sessions have run from spring to spring.

Because elections to the Scottish Parliament and the National Assembly for Wales were scheduled for 7 May 2015, the Act provided for these elections to be held on 5 May 2016, extending the normal four year term to five years. Subsequent elections to the Scottish Parliament will revert to four yearly intervals. But section 1(1) of the Wales Act 2014 provides that subsequent elections to the NAW will take place in every fifth year. The Act did not specify an election date for the Northern Ireland Assembly, but section 7 of the Northern Ireland (Miscellaneous Provisions) Act 2014 postponed the elections to 2016 and provided that subsequent elections will take place in every fifth year thereafter.