5 C.F.R. § 841.502
In this subpart-
Employee means employee as defined in § 842.102 of this chapter or Member as defined in section 8401(20) of title 5, United States Code.
Employee deduction means the portion of the normal cost of FERS coverage which is deducted from an employee's basic pay.
FERS means chapter 84 of title 5, United States Code.
Fund means the Civil Service Retirement and Disability Fund.
Normal cost percentage or Normal cost means the entryage normal cost of the provisions of FERS which relate to the Fund, computed by the Office in accordance with generally accepted actuarial practice and standards (using dynamic assumptions) and expressed as a level percentage of aggregate basic pay. Normal cost percentage or normal cost include both agency and employee contributions.
Social security means old age, survivors and disability insurance under section 3101(a) of the Internal Revenue Code of 1954.
5 C.F.R. §841.502