"A mobile app will be used in Census 2021. It will be a transformation from paper census to digital census," Mr Shah said at an event in Delhi to lay foundation stone of Janganana Bhawan, the office of the census authority. "We can have just one card for all utilities like Aadhaar, passport, bank account, driving licence, voter card. This is a potential," he said.

The Home Minister said there should also be a system that when a person dies, the information is updated in the population data automatically.

An app is being developed indigenously for collecting the data and in Android phones.

Mr Shah also said that the National Population Register is being prepared for the first time in the 2021 census. "NPR will prove to be a game-changer in the country. Digital census has many benefits. If a child takes birth and does not die up to the age of 18, shouldn't he or she be able to vote automatically without applying for a voter id card," Mr Shah said. "It will help in solving several issues like law and order, gender equality," he said.

Rs. 12,000 crore will be spent on the country's first digital census, Amit Shah said. Census 2021 is the sixteenth census in the country and eighth since Independence.

For the first time in the 140-year history of the census in India, data is proposed to be collected through an app and people who conduct door-to-door counting would be encouraged to use their own phone.

A total of 33 lakh enumerators, the persons who conduct door-to-door counting, would be mobilised for data collection. The exercise is being done in 16 languages to facilitate people in filling their details properly, Mr Shah said.

In March this year, the government had announced that the next census will be conducted in two phases with March 1, 2021 as the reference date. For Jammu and Kashmir and snow-bound areas of Himachal Pradesh and Uttarakhand, the reference date shall be the first day of October, 2020, the notification said.

A pre-test of Census 2021, which began on August 12, will go on till the end of this month.