Section 16(4)(xii) in National Savings Certificates (VIII Issue) Rules, 1989
(xii)[ 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 October, 2017] [Inserted by Notification No. G.S.R. 863(E), dated 30.6.2017 (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.