50 U.S.C. § 3518a

The special accrual rates provided by section 2153 of this title and by section 3518 of this title for computation of the annuity of an individual who has served abroad as an officer or employee of the Central Intelligence Agency shall be used to compute that portion of the annuity of such individual relating to such service abroad whether or not the individual is employed by the Central Intelligence Agency at the time of retirement from Federal service.