Section 847.903 - How is the monthly reduction to the retirement annuity computed?(a) The reduction equals: (1) The difference in the present value of the immediate annuity with credit for NAFI service and the deferred annuity without credit for NAFI service, divided by(2) The present value factor for the retiree's attained age (in full years) at the time of retirement.(b) The reduction computed in paragraph (a) of this section is rounded to the next higher dollar.