UK parliamentary by-elections

To be able to stand as a candidate at a UK Parliamentary by-election in Great Britain, the person must, on the day they are nominated and on polling day, be: 

• at least 18 years old, and
• either a British citizen, a citizen of the Republic of Ireland 
• or an eligible Commonwealth citizen

Citizens of other countries are not eligible to become a Member of the UK Parliament.

There is no requirement in law for the candidate to be a registered voter in the UK.

Apart from meeting the qualifications for standing for election, the candidate must also not be disqualified from standing at the time of nomination and on the day of the election. The full range of disqualifications is complex, more information is available in the Commission’s guidance for candidates and agents.

The earliest that a person can officially become a candidate is the day on which the vacancy occurs. If a person has already declared themselves a candidate at the election, they will be a candidate on this day.

If they declare that they will be a candidate at the elections after this day, they become a candidate on that day, or the date they formally submit their nominations papers – whichever is earliest.

Candidates can start campaigning at any time. They do not have to wait until they are validly nominated to declare that they will run for election, to ask people to support them or publish campaign material.

Election spending limits apply from the day after a person officially becomes a candidate.

By law, candidates, parties and non-party campaigners must use ‘imprints’ on all their printed campaign material. An imprint includes the name and address of: 

• the printer 
• the promoter (the person who caused the material to be published) 
• anyone else on whose behalf it has been published

It must be included on all printed material such as posters, placards and leaflets. This is so that electors can be clear about the source of the campaign material. It is an offence not to include an imprint on printed election material.

While it is not currently a legal requirement, the Electoral Commission recommends that candidates, parties and non-party campaigners, wherever possible, place an imprint on their digital materials (e.g. websites, emails and social media platforms). Voters need to know who is targeting them with political messages online.

The UK Government's Elections Act 2022 introduced the imprint requirement for digital political material, which will apply year round. It is due to come into effect in November 2023.

It is illegal to make a false statement about the personal character of a candidate to influence the result of the election. The police may investigate allegations of the specific electoral offence of making a false statement.

Rules about defamation also apply to election materials. Defamation issues are a matter for the civil courts.

The Electoral Commission does not have a regulatory role in relation to the content of campaign material, or what candidates say about each other. However, we do encourage all campaigners to undertake their vital role responsibly and to support campaign transparency.

The spending limit for candidates during the regulated period at a UK Parliamentary by-election is £100,000.

The regulated period begins the day after officially becoming a candidate, and ends on polling day. The earliest date someone can officially become a candidate is the day on which the vacancy occurs. 

If someone’s intention to stand has not been announced by then, they will officially become a candidate on the earlier of:

• the date they or another person declare their intention to stand
• the date when they are nominated

There are rules in place to make sure that spending can be controlled and accurately recorded and reported. 

Candidates usually appoint an agent. It is the agent’s responsibility to fully and accurately report their candidate’s spending. They should ensure they understand the rules and that all spending is properly authorised, recorded and reported. 

During the regulated period, only the following people are allowed to incur election spending: 

• the agent
• the candidate, and
• anyone authorised by the candidate or agent

By ‘incur’ we mean making a legal commitment to spend the money. 

Candidates must only accept donations from a permissible source. A permissible source is:

• an individual registered on a UK electoral register, including overseas electors
• a Great Britain registered political party
• a Northern Ireland registered political party (only if they are standing for election in Northern Ireland)
• most UK registered companies 
• a UK-registered trade union
• a UK-registered building society
• a UK-registered limited liability partnership (LLP) that carries on business in the UK
• a UK-registered friendly society
• a UK-based unincorporated association that is based in and carries on business or other activities in the UK

More information on donation and spending rules for candidates is available in our guidance.

Before accepting any donation of more than £50 for the purpose of meeting candidate spending, the election agent must take all reasonable steps to:

• make sure they know the identity of the true source
• check that the source is permissible

They have 30 days to do this, and must return the donation if they cannot accept it. If they keep a donation longer than 30 days, they are deemed to have accepted it.

After the election the agent must make sure that: 

• all invoices are received within 21 days of the election result being declared
• all invoices are paid on time within 28 days of the election result being declared
• details of the candidate’s spending and donations are reported to the (Acting) Returning Officer within 35 days of the election result being declared, together with a declaration that the return is complete and correct.

The candidate must also submit a declaration confirming that the return is complete and correct to the (Acting) Returning Officer. This must be done within seven days of the return being submitted.

Rules can be found on our guidance for candidates and agents, covering all the information they must include.

A person can vote in a by-election if they are on the electoral register in an area where elections are taking place, and if they are:

• aged 18 or over on polling day
• a British citizen
• an Irish, or qualifying Commonwealth citizen

British citizens living overseas who are registered as overseas voters can vote in parliamentary by-elections. Service voters stationed abroad are eligible to vote in by-elections.

More information on eligibility can be found on our website at www.electoralcommission.org.uk/i-am-a/voter.

In some cases, voters may be eligible to register at two different addresses. However, a person cannot vote in more than one place in a parliamentary by-election. 

Yes. Since May 2023, voters across Great Britain voting in a UK parliamentary by-election or general election are required to bring photo ID to vote in person in a polling station, following new requirements introduced by the Elections Act. A new form of free ID, the Voter Authority Certificate, is available for those who do not have another type of accepted ID.

Accepted forms of photo ID at polling stations include a UK, European Economic Area (EEA) or Commonwealth passport; a UK or EEA drivers’ licence; and some concessionary travel passes, such as an older person’s bus pass or an Oyster 60+ card. The full list is available here. Those that do not have an accepted form can apply for free voter ID.

Voters will be able to use expired ID if they are still recognisable from the photo.

Anyone without an accepted form of ID can apply for a free Voter Authority Certificate at voter-authority-certificate.service.gov.uk, or by requesting a paper form from their local council, or local electoral registration office if they live in Scotland.

The voting system used to elect an MP in a by-election is ‘first past the post’.

• Voters can choose from a list of candidates on the ballot paper who will either be part of a political party or standing as an independent candidate. In order to cast a vote, a voter should simply put an X (a cross) next to the one candidate that they wish to vote for. 
• Under this system, the candidate with the most votes is elected. 

There are a few options available for voting. Voters can vote in person, by proxy or by post.

To vote in person, voters will need to arrive at their designated polling station between 7am and 10pm on polling day. Before polling day, voters will be sent a poll card, which includes details of where their polling station is. Voters can only vote at the polling station specified on this card.

If voters do not wish, or are unable, to go to a polling station, they may apply for a postal vote or a proxy vote. 

Proxy voting is when a voter asks someone they trust to vote on their behalf. They need to complete and sign a proxy application form and return it to their local electoral registration office by the deadline. Their proxy will need to show an accepted form of ID at the polling station before they can vote.

Voters may apply for a postal vote for a specific election, a specific period of time, or for all elections. They need to complete and sign a postal vote application form and return it to their local electoral registration office by the deadline.

Polling stations are open between 7am and 10pm. Any voter who is in a queue at the polling station waiting to vote at 10pm will still be able to vote.

Voters will need to bring an accepted form of ID in order to vote.

Before polling day, voters will be sent a poll card, which includes details of where their polling station is. Voters can only vote at the polling station specified on this card.

Only anonymous voters need to bring their poll card to the polling station, though bringing it may speed up the process for all voters. Anonymous voters do not need to bring photographic ID but must have an Anonymous Elector’s Document.

Polling station staff will be on hand to explain the ballot paper and how to vote.

The (Acting) Returning Officer has the responsibility for counting the votes cast in their respective constituency. The relevant local authority will be able to provide projected count times.

To support electoral administrators with the count process, we have published guidance.

There are four stages to the count process:

1. The postal ballot boxes and ballot boxes from the polling stations arrive at the count venue
2. Staff carry out a verification process and ensure that the number of postal ballot papers and ballot papers matches the numbers recorded at postal vote opening sessions, and by the Presiding Officer at the polling station respectively
3. The votes are counted, and the results are declared by the (Acting) Returning Officer
4. The (Acting) Returning Officer will announce the name of the candidate with the most votes as duly elected