((a)) ** Estimates of annual appropriations** The Director shall prepare the estimates of the annual appropriations required to be made to the fund.
((b)) ** Actuarial valuations** The Director shall cause to be made actuarial valuations of the fund at such intervals as the Director determines to be necessary, but not less often than every five years.
((c)) ** Changes in law affecting actuarial status of fund** Any statute which authorizes—
((1)) new or increased benefits payable from the fund under this subchapter, including annuity increases other than under ;
((2)) extension of the coverage of this subchapter to new groups of employees; or
((3)) increases in pay on which benefits are computed;
((d)) ** Authorization** There is hereby authorized to be appropriated to the fund for each fiscal year such amounts as may be necessary to meet the amount of normal cost for each year that is not met by contributions under .section 2021(a) of this title
((e)) ** Unfunded liability; credit allowed for military service** There is hereby authorized to be appropriated to the fund for each fiscal year such sums as may be necessary to provide the amount equivalent to—
((1)) interest on the unfunded liability computed for that year at the interest rate used in the then most recent valuation of the system; and
((2)) that portion of disbursement for annuities for that year that the Director estimates is attributable to credit allowed for military service,