The director may enter into an agreement with the United States secretary of health and human services for federal administration of a program of state supplementary assistance to prescribed categories of persons who are, or would be except for the amount of income they receive from other sources, receiving federal supplemental security income. The agreement may authorize the secretary to make rules, in addition to and not in conflict with state laws and regulations, respecting eligibility for or the amount of state supplementary assistance paid under this section as the secretary finds necessary to achieve efficient and effective administration of both the basic federal supplemental security income program and the state supplementary assistance program administered by the secretary under the agreement. The agreement shall provide for the state of Iowa to reimburse the federal government, from funds appropriated for that purpose, for state supplementary assistance paid by the federal government pursuant to the agreement.