NEW DELHI: The Centre will begin a mammoth exercise next month to revisit 25 crore households across the country to seed Aadhaar numbers into the National Population Register (NPR) database and update the NPR data . The Rs 951 crore exercise is expected to finally link the NPR with Aadhaar data and will be completed by March 2016, a senior home ministry official told ET.As per present data, 28.89 crore people have given their biometrics for NPR. Of these, Aadhaar numbers have been generated for nearly 21 crore persons. The Unique Identification Authority of India UIDAI ), which issues Aadhaar numbers, has captured biometrics of nearly 82 crore persons.“By going door-to-door for the NPR updation exercise with pre-printed booklets, the details given by persons during the 2011 census will be crosschecked to see if the same person still lives at the address. Also, in case the person has an Aadhaar number , the same will be recorded and seeded into the existing NPR data,” said the official. This is not an exercise to determine citizenship but to update NPR record of the usual residents of the country, the official said. “In scale, at a cost of Rs 951 crore, this is virtually a repeat of the Census exercise,” he said.The Centre aims to avoid duplication in collection of biometric details in the future through this exercise. After the house-to-house check, it will know how many people still do not have an Aadhaar number and are yet to provide their biometrics to either NPR or UIDAI.The home ministry has approved this exercise although there is no Cabinet approval to its Resident Identity Card (RIC) project – the final step in the NPR process. The Centre aimed to issue RIC to 82 crore persons above 18 years of age, complete with the Aadhaar number, upon completion of NPR and UIDAI enrolments.However, a parliamentary standing committee in April questioned the utility of RICs, pointing out that Election Identity Cards (EIC) are already issued to residents in the same age group. “Linking of Aadhaar numbers with EIC is underway and therefore EIC will also have biometric details. In view of the committee, this arrangement seems sufficient,” the committee said in its report.The committee said all possible steps should be taken to avoid the duplication of efforts between different agencies of the government as well as avoidable expenditure from public exchequer. The home ministry’s NPR project had lost the turf to the UIDAI project. While NPR was to be done by the Centre all over India, later on the states were divided between the RGI and UIDAI. However, UIDAI was allocated as many as 24 states for collection of biometric details of residents.