Section 16(4)(v) in National Savings Certificates (VIII Issue) Rules, 1989
(v)[ 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 December, 2011 [1st day of April, 2012] [Inserted by Notification F.NO.1/7/2011-NS-II, dated 25.11.2011 (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.