What is delimitation, and why does it matter for Tamil Nadu?

• Two jobs: share Lok Sabha seats among the States by population, and redraw constituencies so each has about the same population (Articles 81, 82 and 170, with similar rules for Assemblies).
• The freeze: the 42nd Amendment (1976) froze each State’s seats on the 1971 census until the first census after 2000; the 84th Amendment (2001) extended it until the first census after 2026 is published. The last Delimitation Commission was set up in 2002; its orders were final in 2008.
• Women’s reservation: the 106th Amendment (2023) reserves one-third of Lok Sabha and Assembly seats for women, on the basis of the first census after it, and so after delimitation.

• Seats: 39 Lok Sabha seats of 543 (7.18%); 234 Assembly seats. Population, 2011 census: 7,21,47,030 (PRS).
• PRS projection on the 2011 census: 32 seats (5.84%) if the Lok Sabha keeps 543 seats; 48 seats (5.90%) if every State’s seats rise by 50%.
• This is PRS Legislative Research’s calculation for the withdrawn bills. It is not a decision, and none exists for the 2027 census because it has not been counted.

• The concern, as Tamil Nadu’s government and the DMK state it: a population-based reshuffle could cut the share of States that held down population growth (as reported). On 12 August 2026 the Assembly asked the Union government to freeze Lok Sabha seats at 543, keep each State’s share, keep the 2.2:1 Lok Sabha to Rajya Sabha ratio, and give women one-third of seats in 2029 on the existing 543.
• The vote: Chief Minister C. Joseph Vijay moved the resolution. The DMK backed it; the AIADMK, PMK, DMDK and BJP opposed it (as reported). The AIADMK’s Edappadi K. Palaniswami said delimitation could go ahead without taking Tamil Nadu below 7.18%.
• The Union government’s case (Home Minister, Lok Sabha, 17 April 2026): the Constitution provides for delimitation; it serves “one person, one vote, one value”; raising every State’s seats by 50% would keep shares, with the five southern States going from 23.76% to 23.87%.

Decided

• Seat numbers stay frozen until the first census after 2026 is published (Constitution, 84th Amendment).
• The 2026 package of bills did not pass: the Constitution (131st Amendment) Bill was rejected on 17 April 2026 and the Delimitation Bill, 2026 was withdrawn.
• The census reference date is 00:00 hours of 1 March 2027.

Not decided

• When a Delimitation Commission is set up, and which census it uses.
• The total size of the Lok Sabha and how seats are shared among States.
• Tamil Nadu’s seat count after any change, and the date women’s reservation takes effect.

• Phase I is house-listing. In Tamil Nadu self-enumeration was set for 17 to 31 July 2026 and house-to-house listing for 1 to 30 August 2026 (Director of Census Operations, Tamil Nadu).
• Phase II, the population count, is scheduled for February 2027, with 1 March 2027 as the reference date. Exact dates for Tamil Nadu: not announced in the sources we checked.
• Timing: PRS says delimitation on the 2027 census is unlikely to be finished before the 2029 Lok Sabha elections; the Home Minister said on 17 April 2026 that it cannot be completed before 2029.