(A) In applying the table of benefits in effect in December 1978 under this section for purposes of the last sentence of paragraph (4), such table, revised as provided by subsection (i), as applicable, shall be extended for average monthly wages of less than $76.00 and primary insurance benefits (as determined under subsection (d)) of less than $16.20.
(B) The Commissioner of Social Security shall determine and promulgate in regulations the methodology for extending the table under subparagraph (A).