“Some Federal retirees receive a temporary ‘annuity supplement’ in addition to their basic annuity. Section 8421(c) of Title 5 governs how OPM must treat an annuity supplement when a court order expressly divides an employee annuity (in divorce proceedings, for example). Under that provision, OPM must apportion the annuity supplement owed to a Federal retiree ‘in the same way’ as a basic annuity. Consistent with the plain language of section 8421(c), OPM has included annuity supplements in the computation of a court-ordered apportionment when a court order expressly divides an employee annuity, regardless of whether the court order explicitly references the annuity supplement.”
“The question presented in this appeal is whether the board misinterpreted 5 U.S.C. ยง 8421(c) by concluding that OPM cannot divide the annuity supplement at all, unless the division of the annuity supplement is expressly provided for in a court order.”