The pension accumulation fund shall be the fund in which shall be held the reserves on all annuities in force and from which shall be paid all annuities and all benefits in lieu of annuities under this chapter. If a beneficiary is restored to membership, his annuity reserve shall be transferred from the pension accumulation fund to the annuity savings fund and credited to his individual account therein. The pension accumulation fund shall also be the fund in which shall be accumulated all reserves for the payment of all pensions and other benefits payable from contributions made by employers and from which shall be paid all such pensions and other benefits, as follows:

(1) The contribution of employers of members shall consist of a percentage of the earnable compensation of members to be known as the normal contribution and an additional percentage of such earnable compensation to be known as the accrued liability contribution. The rate of such contribution shall be fixed on the basis of the liabilities of the retirement system as shown by actuarial valuation;

(2) The normal contribution rate shall be determined after each actuarial valuation. Until all accrued liability contributions have been completed, the normal contribution rate shall be determined on the basis of regular interest and the tables last adopted by the board of trustees, as the uniform and constant percentage of the earnable compensation of the average new entrant member which, if contributed on the basis of his prospective earnable compensation throughout his entire period of active service, would be sufficient to provide for the payment of any pension payable on his account. After all accrued liability contributions have been completed, the normal contribution rate shall be the rate of the earnable compensation of all members obtained by deducting from the total liabilities of the pension accumulation fund the amount of the funds in hand standing to the credit of the pension accumulation fund, and dividing the remainder by 1 percent of the present value of the prospective future earnable compensation of all members;

(3) Immediately following the actuarial valuation of June 30, 1961, the percentage accrued liability contribution rate shall be computed as the rate of the total earnable compensation of all members which is equivalent to 4 percent of the total liability of the pension accumulation fund in excess of the funds in hand standing to the credit of the pension accumulation fund and which is not dischargeable by the normal contributions payable in respect to members on that date, during the remainder of their active service. Thereafter, the amount of funds for the credit of each annual accrued liability contribution account shall be at least 3 percent greater than the amount placed to the credit of the accrued liability contribution account in the previous year, on the basis of the rate determined as of June 30, 1961; and in no event shall the accrued liability contribution in any year be less than the amount which, when combined with the normal contributions and the amount of funds in hand standing to the credit of the pension accumulation fund, will provide all payments and transfers from the pension accumulation fund as required by this Code section during the year then current. The accrued liability contribution shall be discontinued as soon as the amount of the funds standing to the credit of the pension accumulation fund equals the present value, as actuarially computed, and approved by the board of trustees, of the total liabilities of the pension accumulation fund less the present value of the normal contributions to be made at the normal contribution rate then in force in respect to all persons who are members at that time;

(4) The state's share of employer contributions, which is to be borne by appropriation from the state, payable to the board of trustees, shall consist of the normal and accrued liability contributions based on the part of the earnable compensation of members payable from funds of the Board of Regents of the University System of Georgia or other funds of the state, but excluding any appropriations made to the State Board of Education, at the rates determined under this Code section. The balance of the cost for pensions, consisting of the normal and accrued liability contributions at the rates determined under this Code section, shall be borne by the employers having contributing members in their employ, including local units of administration for all members in their employ; and each such employer shall pay, from any funds available to such employer expressly including funds derived from the state under Article 6 of Chapter 2 of Title 20, the "Quality Basic Education Act," such contributions to the board of trustees, immediately upon coming due, which contributions shall be credited to the pension accumulation fund; and

(5) The compensation of a member referred to in this Code section shall include any compensation derived from grants and contracts made by outside agencies with an employer. Such compensation is subject to the employer contribution rate. The outside agencies supplying the grants or entering into the contracts shall pay the applicable employer contributions rate to the employer, who shall pay such contribution to the board of trustees.