National Savings Certificate requires Aadhaar as unique identifier; enrolment proof accepted; submit Aadhaar by deadline. The amendment substitutes the definition of 'Aadhaar number' and inserts rule 4A making the Aadhaar number the unique identifier for establishing the identity of National Savings Certificate account holders; where Aadhaar is not assigned, proof of enrolment must be submitted, and depositors who had not given Aadhaar at application were required to submit it to the Post Office Savings Bank on or before 31 December 2017.