; and (2) the partially reinstated surcharge reinstated pursuant to paragraph (1) shall be considered a part of the rate base for purposes of determining the percentage changes in rates when the Postal Service files a notice of rate adjustment. (b) Subsequent rate increases The reinstatement described under subsection (a)(1) may not affect the calculation of the Postal Service’s maximum rate adjustment authority under subpart C of part 3010 of title 39, Code of Federal Regulations, for purposes of any rate increase that occurs following such reinstatement. (c) Postal Regulatory Commission authority not affected Nothing in this section shall be construed as affecting the authority of the Postal Regulatory Commission to, by regulation, make such modification or adopt such alternative system for regulating rates and classes for market-dominant products as provided under section 3622 of title 39, United States Code. 208. Completion of initial rate regulation review The Postal Regulatory Commission shall complete the initial review of the system for regulating rates and classes for market-dominant products established under section 3622 of title 39, United States Code, such that any final rule making a modification or adopting an alternative system for regulating rates and classes for market-dominant products as necessary to achieve the objectives in subsection (b) of such section is issued not later than January 1, 2019. 209. Review of Postal Service cost attribution guidelines Not later than April 1, 2019, the Postal Regulatory Commission shall initiate a review of the regulations issued pursuant to sections 3633(a) and 3652(a)(1) of title 39, United States Code, to determine whether revisions are appropriate to ensure that all direct and indirect costs attributable to competitive and market-dominant products are properly attributed to those products, including by considering the underlying methodologies in determining cost attribution and considering options to revise such methodologies. If the Commission