(1) The contribution of employers of members shall consist of a percentage of the earnable compensation of members to be known as the normal cost contribution and an additional percentage of such earnable compensation to be known as the unfunded 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, as provided for in Code Section 47-3-23, subject to the provisions of Code Section 47-20-10;

(2) 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 cost and unfunded 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 cost and unfunded 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

(3) 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.