such regulations for purposes of this subsection as may be necessary or appropriate for determining proper allocation to specified medical research of the portion of any credit allowed to a taxpayer for a taxable year under this section. . (b) Conforming amendment Section 1324(b) of title 31, United States Code, is amended by inserting 41(i), after 6428, . (c) Effective date The amendments made by this section shall apply to taxable years beginning after December 31, 2022.