Section 847.605 - Methodology for determining the present value of annuity with service credit(a) OPM will determine the present value of the annuity including service credit for NAFI service under paragraph (b) or (c) of this section.(b) In cases in which the annuity is payable to a retiree, the present value under paragraph (a) of this section equals the monthly annuity rate including credit for the NAFI service as of the date of computation under § 847.603 times the present value factor for the retiree's age on that date.(c) In cases in which the annuity is payable to a survivor, the present value under paragraph (a) of this section equals the monthly annuity rate including credit for the NAFI service as of the date of computation under § 847.603 times the present value factor for the survivor's age on that date.