What is a bypoll (by-election) and when is one held?

A by-election, or bypoll, fills a vacancy in the Lok Sabha, the Rajya Sabha, a state Legislative Assembly or a Legislative Council between general elections. Under the Representation of the People Act, 1951, the Election Commission issues a notification calling on the constituency to elect a person to fill the vacancy.

A seat becomes vacant in several ways. A member can resign in writing to the Speaker or Chairman, and the seat falls vacant once it is accepted. A member can be disqualified under Article 102. A House can also declare a seat vacant if the member is absent without permission for 60 days. A member's death, or an election being declared void, also creates a vacancy. See the upcoming bypolls and other elections on this site.

Section 151A says a by-election "shall be held within a period of six months from the date of the occurrence of the vacancy". The provision was inserted in 1996 and covers vacancies in the Council of States, the House of the People, State Assemblies and State Councils.

There are two exceptions. The six-month rule does not apply where the remainder of the member's term is less than one year, or where the Election Commission, in consultation with the Central Government, certifies that it is difficult to hold the by-election within that period.

The second exception has been litigated. A Bombay High Court judgment of 13 December 2023 considered the six-month rule and the one-year proviso. We do not give a count of delayed by-elections because we have not verified one.

A member chosen to fill a casual vacancy in the Rajya Sabha serves the remainder of their predecessor's term (section 154(3)). For the Lok Sabha and Assemblies, the winner sits for the remainder of that House's term, which runs five years from its first meeting unless it is dissolved sooner.

A person can contest more than one seat, and this is a common source of by-elections. Section 33(7) limits a candidate to two constituencies in a general election to the House of the People, and likewise for Assemblies. If someone is elected to more than one seat, section 70 provides that unless they resign all but one within the prescribed time, all the seats become vacant.

• Two seats in the same kind of House: Rule 91 of the Conduct of Elections Rules, 1961 sets the time at fourteen days from the date of election.
• A seat in Parliament and a state legislature at once: under the Prohibition of Simultaneous Membership Rules, 1950, the Parliament seat becomes vacant unless the state seat is resigned within fourteen days of the later gazette publication. For two different states the period is ten days.
• A seat in both Houses of Parliament: the member may say within ten days which they wish to keep; otherwise the Council of States seat becomes vacant (section 68). A member of one House who is elected to the other loses the first seat when they are chosen (section 69).

The Election Commission's FAQ says that in a by-election the Model Code applies only in the area of the constituency if it lies within a State Capital, Metropolitan City or Municipal Corporation. In all other cases it is enforced across the entire district or districts that cover the constituency. Read the Model Code of Conduct explainer for the rules themselves.