Thirty days prior to the time the State Board of Education fixes the minimum schedule of teachers' salaries for the ensuing year, the normal and accrued contribution rates, as determined on the basis of the last annual actuarial valuation, shall be certified by the board of trustees to each employer having members in its employ. Each such employer other than the state shall include in its budget filed with the State School Superintendent amounts equal to the prospective contributions on account of contributing members in its employ for the ensuing year. The Board of Regents of the University System of Georgia in its estimates of the funds necessary for the operation of its respective units, which estimates are submitted to the Governor and General Assembly, shall include a request for an appropriation payable to the board of trustees in an amount equal to the portion of the normal and accrued liability contributions payable from funds of the Board of Regents of the University System of Georgia or from other state funds and for an additional amount as expense for the operation of the retirement system. The General Assembly shall make appropriations to the board of trustees sufficient to provide for such contributions as a part of the earnable compensation of members payable from such funds and for the necessary expenses of carrying out this chapter.