describes the criteria to be applied by the State in determining the eligibility of any individual for assistance under the plan and in any event requires a determination by the State agency to the effect that (A) such individual’s ability to continue his employment would be significantly inhibited without such assistance and (B) such individual’s earnings are not sufficient to allow him to provide for himself a reasonable equivalent of the cash and other benefits that would be available to him under this subchapter and subchapters XIX and XX in the absence of those earnings;