; and (B) in making the determination under subparagraph (A), shall— (i) take into account the provisions of this Act and the amendments made by this Act; (ii) comply with the requirements under clauses (i) and (ii) of paragraph (3)(B); and (iii) take into account, and incorporate into any adjustment to rates for underwater products identified under subparagraph (A) of paragraph (2), the impact quantified under subparagraph (B) of that paragraph. (5) Application of new rates to underwater products (A) In general If the Commission modifies the system for regulating rates and classes for market-dominant products established under section 3622 of title 39, United States Code, or adopts an alternative system for regulating rates and classes for market-dominant products, the Commission— (i) may not apply any new rates under the modified or alternative system to underwater products until the Commission has— (I) completed the study under paragraph (2); and (II) complied with subparagraph (C) of paragraph (3); and (ii) in order to offer as many underwater products as possible for as long as possible, shall establish a process to gradually phase in the application of any new rates to underwater products. (B) Retroactive applicability If, before the date of enactment of this Act, the Commission modifies the system for regulating rates and classes for market-dominant products established under section 3622 of title 39, United States Code, or adopts an alternative system for regulating rates and classes for market-dominant products, the Commission— (i) shall, effective 90 days after the date of enactment of this Act, apply the rates for underwater products that were in effect on the day before the date on which the modified or alternative system took effect