The freeze on delimitation of Parliamentary constituencies based on 1971 census was extended till the first census after ______ by the 84th Constitutional Amendment Act, 2001.

Delimitation freeze: (a) 42nd Amendment (1976): Froze Lok Sabha/Assembly seats based on 1971 census till 2001 to encourage population control, (b) 84th Amendment (2001): Extended freeze till first census after 2026, (c) 87th Amendment (2003): Allowed delimitation based on 2001 census for Assembly constituencies only (not Lok Sabha). Rationale: Prevent penalization of States that controlled population growth; ensure political representation not distorted by demographic changes. Next delimitation expected post-2026 census.