supplemental liability
(27) the term “supplemental liability” means the estimated excess of— (A) the actuarial present value of all future benefits payable from the Fund under this chapter based on the service of current or former employees or Members, over (B) the sum of— (i) the actuarial present value of deductions to be withheld from the future basic pay of employees and Members currently subject to this chapter pursuant to section 8422; (ii) the actuarial present value of the future contributions to be made pursuant to section 8423(a) with respect to employees and Members currently subject to this chapter; (iii) the Fund balance as of the date the supplemental liability is determined, to the extent that such balance is attributable— (I) to the System, or (II) to contributions made under the Federal Employees’ Retirement Contribution Temporary Adjustment Act of 1983 by or on behalf of an individual who became subject to the System; and (iv) any other appropriate amount, as determined by the Office in accordance with generally accepted actuarial practices and principles;