Election law | Lok Sabha by-elections

Section 149: Casual vacancies in the House of the People

Section 149 of the Representation of the People Act, 1951 provides for filling a casual vacancy in the Lok Sabha (House of the People) through an election notified by the Election Commission of India. It also specifies how vacancies in constituencies reserved for Scheduled Castes or Scheduled Tribes must be filled.

In brief: A vacancy caused by a seat becoming vacant, being declared vacant, or an election being declared void is ordinarily filled through a by-election. Section 151A prescribes the general six-month timeframe and important exceptions; Section 149 itself does not set a fixed six-month deadline.

Section 149: statutory text

Sub-section (1): Notification and election to fill the vacancy

(1) When the seat of a member elected to the House of the People becomes vacant or is declared vacant or his election to the House of the People is declared void, the Election Commission shall, subject to the provisions of sub-section (2), by a notification in the Gazette of India, call upon the Parliamentary constituency concerned to elect a person for the purpose of filling the vacancy so caused before such date as may be specified in the notification, and the provisions of this Act and of the rules and orders made thereunder shall apply, as far as may be, in relation to the election of a member to fill such vacancy.

Sub-section (2): Vacancies in reserved constituencies

(2) If the vacancy so caused be a vacancy in a seat reserved in any such constituency for the Scheduled Castes or for any Scheduled Tribes, the notification issued under sub-section (1) shall specify that the person to fill that seat shall belong to the Scheduled Castes or to such Scheduled Tribes, as the case may be.

Meaning of a casual vacancy

A casual vacancy is a vacancy arising in an existing parliamentary seat otherwise than through the ordinary general election held upon the expiry or dissolution of the House. Section 149 expressly covers three situations: a seat becomes vacant, a seat is declared vacant, or the member's election is declared void. Depending on the governing law and facts, vacancies may arise from resignation, death, disqualification, or an election judgment.

How a Lok Sabha by-election is initiated

Vacancy arises: The parliamentary seat becomes or is declared vacant, or the election is declared void.
Gazette notification: The Election Commission calls upon the concerned parliamentary constituency to elect a replacement through a notification published in the Gazette of India.
Election programme: The applicable statutory election provisions, rules, orders and notified schedule govern nominations, scrutiny, withdrawal, polling and counting.
Reserved-seat requirement: For a Scheduled Caste or Scheduled Tribe reserved constituency, the notification must specify the corresponding eligibility requirement under sub-section (2).

When must a casual vacancy be filled?

Section 151A of the Representation of the People Act, 1951 generally requires a by-election for filling a vacancy referred to in Sections 147, 149, 150 and 151 to be held within six months from the date the vacancy occurs. Its proviso excludes this requirement 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 holding the by-election within that period is difficult. The provisions must be read together rather than treating Section 149 as an unconditional deadline.

How are reserved seats treated?

Under Section 149(2), if a vacant Lok Sabha seat is reserved for the Scheduled Castes or Scheduled Tribes, the Gazette notification must state that the person elected to fill it belongs to the relevant constitutionally recognised category. This continues the reservation attached to the constituency; a casual vacancy does not convert a reserved constituency into an unreserved one.

Does the elected replacement receive a fresh five-year term?

No. Under Article 83(2) of the Constitution, the normal duration of the Lok Sabha is five years from its first meeting unless sooner dissolved, subject to constitutional exceptions. A member elected at a by-election serves for the remaining duration of the existing House, rather than starting a new five-year term.

Section 147: Casual vacancies in the Council of States (Rajya Sabha).
Section 150: Casual vacancies in State Legislative Assemblies.
Section 151: Casual vacancies in State Legislative Councils.
Section 151A: Time limit for filling vacancies referred to in Sections 147, 149, 150 and 151.
Article 101 of the Constitution: Vacation of seats in Parliament.
Section 148: Repealed by the Territorial Councils Act, 1956 (Act 103 of 1956), section 66.

Frequently asked questions

Who announces a Lok Sabha by-election?

The Election Commission of India issues the statutory notification calling upon the parliamentary constituency to elect a member under Section 149.

Is a by-election always held within six months?

Section 151A generally prescribes six months but provides express exceptions for a remaining term of less than one year and certified difficulty in conducting the election within that period.

Can a reserved Lok Sabha seat be filled by a candidate outside the reserved category?

No. Section 149(2) requires the notification to specify the relevant Scheduled Caste or Scheduled Tribe qualification for the reserved seat.

Official legislation and election resources

For the statutory text and any subsequent amendments, see India Code and the Legislative Department. For election notifications, programmes and results, consult the Election Commission of India and the Gazette of India. See also the Representation of the People Act, 1951 index.

Updated 5 October 2026. This article explains the general statutory position; individual election notifications and applicable legal provisions govern particular cases.