In a notification, the Registrar General of India said the decision has been taken as the exercise to enumerate citizens in the NRC, a list of Assam's residents, could not be completed within the specified date of June 30.
The final list of the NRC will be published on August 31.
For the purpose of NPR, a usual resident is defined as a person who has resided in a local area for past six months or more or a person who intends to reside in that area for the next six months or more.
The Centre on Tuesday said it was discussing with state governments the preparations for updating the National Population Register from April 1 to September 30. Union Minister of State for Home Nityanand Rai said in the Lok Sabha that no document will be collected during the exercise, which will be carried out along with the house-listing phase of Census 2021.
Rajasthan Chief Secretary D B Gupta said he and the representatives of a few other states raised objections to a few questions to be asked by enumerators during the NPR exercise. He said the central government officials told them that answers to all such questions are not mandatory.