The corporation may revise such schedules whenever it determines that revised schedules are necessary. Except as provided in section
1322a
(f) of this title, in order to place a revised schedule described in subparagraph (A) or (B) in effect, the corporation shall proceed in accordance with subsection (b)(1) of this section, and such schedule shall apply only to plan years beginning more than 30 days after the date on which a joint resolution approving such revised schedule is enacted.