50 U.S.C. § 435b(a)(7) (2010) (Title 50—Chapter 15: National Security--Subchapter F: Access to Classified Information)
(a) Definitions. In this section:
(7) The term "periodic reinvestigations" means investigations conducted for the purpose of updating a previously completed background investigation—
(A) every 5 years in the case of a top secret clearance or access to a highly sensitive program;
(B) every 10 years in the case of a secret clearance; or
(C) every 15 years in the case of a Confidential Clearance.