De Jure Method UPSC relevant
Under the de jure method, each person is counted at their place of usual residence, regardless of where they happen to be at the census moment. Its practical advantage is that enumeration can be spread over many days without risk of double counting travellers.
India's population census is not purely de jure — it uses an extended de facto canvasser method — but de jure logic appears in related instruments: the National Population Register is a register of 'usual residents' (persons who have lived in a local area for six months or more, or intend to), and census questions on normal residence, migration and household membership rest on usual-residence concepts. Knowing which logic applies explains why a visitor present on census night and a usual resident abroad are treated differently in 2027.