In accordance with waivers of federal law that are granted by the secretary of the U.S. department of health and human services, the department of public health and human services may provide extended eligibility for medical assistance for a period of time established by the department by rule for persons receiving section 1931 medicaid benefits, as defined in 53-4-602, who lose eligibility because of increased earned or unearned income to the assistance unit, as that term is defined in the rules of the department, provided that the family’s income does not exceed a percentage of the federal poverty level established by the department by rule.