By-election timetables
Election rules state elections must be held using a set timetable. This briefing explains the timetable for by-elections to the UK Parliament.
All elections follow a statutory timetable. This sets out key stages, including when notice of the election is published, when nominations can be submitted, and when polling day takes place.
Triggering the timetableThe timetables for UK Parliament elections and by-elections are triggered by the issue of writs. The writs tell the relevant returning officer to hold an election to return an MP.
The timetables for other elections and by-elections operate differently and this note only considers those for the UK Parliament.
By-electionsTo start the election timetable for a by-election the House of Commons must pass a motion for the Speaker to make out the warrant for the issue of a writ.
There is no fixed deadline for holding a by-election after a seat becomes vacant. By convention an MP of the party that previously held the seat, usually a whip, will initiate the required motion at a time of their choosing. The returning officer is then responsible for determining and implementing the by-election timetable.
The timetable for parliamentary by-elections is set at 21 to 27 working days. This is designed to allow the poll to be held on a Thursday, whenever the writ is moved. Dates of writs and by-elections since 2005 are in the Library briefing, UK parliamentary by-elections since 1945.
Model timetableIn a by-election the returning officer selects the closing date for nominations. Polling day must be no earlier than the 17th day and no later than the 19th day after nominations close.
The rules on when nominations close for a by-election state that nominations can be received between the hours of 10am and 4pm from the day after the publication of the notice of election (which can happen on day 1, 2 or 3). The earliest the notice can be published is day 1, the same day as the receipt of the writ.
Nominations must close “not earlier than the third day after the date of publication of the notice of election" and the deadline for the close of nominations is 4pm “no later than the seventh day after that on which the writ is received.”
This means that the earliest the returning officer can close nominations is day 4 and the latest is day 8, depending on when the returning officer publishes the notice of election.
With polling day required to be 17, 18, or 19 days after the close of nominations, the minimum time for polling day is 17 days after day 4 and the maximum time period is 19 days after day 8. This gives a range of 21 to 27 working days for a by-election.
The possible range is set out in the table below.
General electionsThe timetable for a general election is set at 25 working days. General elections are traditionally held on a Thursday, but there is no legal requirement for this. The dissolution of Parliament and the issue of the writs are timed so that they happen on a day that will cause polling day to be on a Thursday.
The Library briefing, Election timetables gives more information on general election timetables.