Any cash payments which are made by a State (or political subdivision thereof) on a regular basis to individuals who are receiving benefits under this subchapter or who would but for their income be eligible to receive benefits under this subchapter, as assistance based on need in supplementation of such benefits (as determined by the Commissioner of Social Security), shall be excluded under section
1382a
(b)(6) of this title in determining the income of such individuals for purposes of this subchapter and the Commissioner of Social Security and such State may enter into an agreement which satisfies subsection (b) of this section under which the Commissioner of Social Security will, on behalf of such State (or subdivision) make such supplementary payments to all such individuals.