Section 837.506 - Computation of redetermined annuity for former employees of nonappropriated fund instrumentalities(a) The redetermined annuity of a former employee of a nonappropriated fund instrumentality who elected CSRS or FERS coverage under 5 CFR part 847 , subpart D, is recomputed under 5 CFR part 847 , subpart F.(b) The redetermined annuity of a former employee of a nonappropriated fund instrumentality who elected CSRS or FERS retirement credit under 5 CFR part 847 , subpart H, is recomputed under 5 CFR part 847 , subpart I.68 FR 2178, Jan. 16, 2003