34 U.S.C. § 20918
Periodic in person verification
A sex offender shall appear in person, allow the jurisdiction to take a current photograph, and verify the information in each registry in which that offender is required to be registered not less frequently than—
(1)
each year, if the offender is a tier I sex offender;
(2)
every 6 months, if the offender is a tier II sex offender; and
(3)
every 3 months, if the offender is a tier III sex offender.
( Pub. L. 109–248, title I, § 116 , July 27, 2006 , 120 Stat. 595 .)