; (B) by striking in subparagraph (B) in the second sentence and inserting in this subsection ; and (C) by striking paragraphs (2) and (3). (d) Performance requirements in case of best available control technology Section 48A(f) of such Code, as amended by this Act, is amended by adding at the end the following: In the case of a retrofit of a unit which has undergone a best available control technology analysis after August 8, 2005, with respect to the removal or emissions of any pollutant which is SO2 or NOx, the removal or emissions design level with respect to such pollutant shall be the level determined in such analysis. . (e) Clarification of reallocation authority Section 48A(d)(4) of the Internal Revenue Code of 1986 is amended— (1) in subparagraph (A)— (A) by striking Not later than 6 years after the date of enactment of this section, the and inserting The ; and (B) by inserting and every 6 months thereafter until all credits available under this section have been allowed after the date which is 6 years after the date of enactment of this section ; (2) in subparagraph (B)— (A) by striking may reallocate credits available under clauses (i) and (ii) of paragraph (3)(B) and inserting shall reallocate credits remaining available under paragraph (3) ; (B) by striking or at the end of clause (i); and (C) by striking clause (ii) and inserting the following: (ii) any applicant for certification which submitted an accepted application has subsequently failed to satisfy the requirements under paragraph (2)(D), or (iii) any certification made pursuant to paragraph (2) has been revoked pursuant to paragraph (2)(E). ; and (3) in subparagraph (C)— (A) by striking clause (i) or (ii) of paragraph (3)(B) and inserting paragraph (3) ; (B) by striking is authorized to and inserting shall