(a) An employee or survivor who elects FERS coverage with credit for NAFI service under §847.421 will receive credit in the FERS annuity for the service represented by any refund of the unexpended balance under §843.202 of this chapter.

(b) The amount of the refund, increased by interest as computed under §842.305(e) of this chapter, will be added to the deficiency computed under §847.604 and collected in accordance with the provisions of §847.609 (pertaining to a monthly reduction in the annuity benefit).