In the event the General Assembly shall have established by law the maximum annual salaries for certain positions for any state agency and shall have appropriated for those positions, no greater salary than that established by law shall be paid to any person occupying the position by making supplemental payments from agency bank funds. However, the salaries may be paid partly from state-appropriated funds and partly from agency bank funds, but the aggregate of the payments shall not exceed the maximum annual salary rate, where it is established by law.