taxable years. (B) No credit amount by reason of cost-of-living adjustment after overall limit first reached No credit amount shall be determined under this section with respect to any qualified investment of a taxpayer in a qualifying business entity for any taxable year after the first taxable year for which the amount determined under subclause (II) of subparagraph (A)(ii) equals or exceeds the amount determined under subclause (I) of such subparagraph. (3) Reduction in credit amount where loan rate exceeds prime rate (A) In general If— (i) the rate of interest (expressed as an annual percentage rate) on a qualified investment which is a qualifying loan, exceeds (ii) the bank prime rate as of the first day of the month in which the loan is entered into (or such other time as the Secretary may specify), then each of the amounts determined under subparagraphs (A) and (B)(i) of paragraph (1) shall be reduced (but not below zero) by the amount which bears the same ratio to such amount as the number of full percentage points by which such rate of interest exceeds such bank prime rate bears to 25. (B) Special rules where qualifying loans treated as part of single investment If 1 or more qualifying loans to which subparagraph (A) applies are treated as part of a single qualified investment under subsection (c)(1), then, for purposes of this subsection— (i) the credit amount under paragraph (1) for such single qualified investment shall be the sum of such credit amounts computed separately for each such qualifying loan and such credit amount computed for all other qualified investments treated as part of such single qualified investment, and (ii) the limitation under paragraph (2) shall be applied to such sum. (C) Rules relating to interest rates (i) Annual percentage rate The Secretary shall prescribe guidance or regulations for the calculation of the annual percentage rate of interest on a loan for purposes of subparagraph (A)(i), including rules which provide for— (I) the calculation of the annual percentage rate