The Indian Constitution came into force on 26 November 1949.

26 November 1949 is when the Constitution was adopted and signed by the Constituent Assembly, but most of its provisions legally commenced later, on 26 January 1950, as stated in Article 394.

26 January 1950 was chosen randomly as Republic Day.

The date was deliberately chosen because 26 January had already been observed since 1930 as 'Purna Swaraj Day', marking India's pledge for complete independence.

The Constitution of India

Article 394

Commencement

This article and articles 5, 6, 7, 8, 9, 60, 324, 366, 367, 379, 380, 388, 391, 392 and 393 shall come into force at once, and the remaining provisions of this Constitution shall come into force on the twenty-sixth day of January, 1950, which day is referred to in this Constitution as the commencement of this Constitution.§

Why this exists

The Constituent Assembly finished and adopted the Constitution on 26 November 1949, but the framers wanted the full document to formally begin on a symbolically important date — 26 January — which had been observed as 'Purna Swaraj' (complete independence) day since 1930. However, certain provisions (like defining citizenship, setting up the Election Commission, and enabling the President's oath) needed to operate right away so that the machinery of the new government — elections, the first President, citizenship status — could be readied in time for the full Constitution to take effect smoothly on Republic Day.

Common misconceptions

Myth: The Indian Constitution came into force on 26 November 1949.
Fact: 26 November 1949 is when the Constitution was adopted and signed by the Constituent Assembly, but most of its provisions legally commenced later, on 26 January 1950, as stated in Article 394.
Myth: 26 January 1950 was chosen randomly as Republic Day.
Fact: The date was deliberately chosen because 26 January had already been observed since 1930 as 'Purna Swaraj Day', marking India's pledge for complete independence.