5 CFR § 1620.20 - Scope.
(a) This subpart applies to:
(1) A justice or judge of the United States as defined in 28 U.S.C. 451;
(2) A bankruptcy judge appointed under 28 U.S.C. 152 or a United States magistrate judge appointed under 28 U.S.C. 631 who has chosen to receive a judges' annuity described at 28 U.S.C. 377 or section 2(c) of the Retirement and Survivors' Annuities for Bankruptcy Judges and Magistrates Act of 1988, Public Law 100-659, 102 Stat. 3910-3921;
(3) A judge of the United States Court of Federal Claims appointed under 28 U.S.C. 171 whose retirement is covered by 28 U.S.C. 178; and
(4) A judge of the Court of Veterans Appeals appointed under 38 U.S.C. 7253.
(b) This subpart does not apply to a bankruptcy judge or a United States magistrate judge who has not chosen a judges' annuity, or to a judge of the United States Court of Federal Claims who is not covered by 28 U.S.C. 178. Those individuals may participate in the TSP only if they are otherwise covered by CSRS or FERS.