The Commissioner of Social Security shall not find that a State has failed to meet the requirements imposed by paragraph (4) of subsection (a) with respect to the levels of its supplementary payments for a particular month or months if the State’s expenditures for such payments in the twelve-month period (within which such month or months fall) beginning on the effective date of any increase in the level of supplemental security income benefits pursuant to section 1382f of this title are not less than its expenditures for such payments in the preceding twelve-month period.