Section 16(4)(viii) in National Savings Certificates (VIII Issue) Rules, 1989
(viii)[ If a certificate is encashed under sub-rule (1) after the expiry of three years from the date of certificate, purchased on or after the [1st day of April 2016] [Inserted by Notification No. G.S.R. 494(E), dated 11.7.2014 (w.e.f. 8.5.1989).], the amount payable, inclusive of interest accrued under rule 15 and after adjustment of discount, shall be as specified in the Table below for a certificate of Rs. 100 denomination and at a proportionate rate for a certificate of any other denomination.