; cost-Sharing Section 1833(a) of the Social Security Act is amended— (1) in paragraph (1)— (A) in subparagraph (S), by striking with respect to and inserting subject to subparagraph (DD), with respect to ; (B) by striking and (CC) and inserting (CC) ; and (C) by inserting before the semicolon at the end the following: , and (DD) with respect to a part B rebatable drug (as defined in paragraph (2) of section 1834(x)) for which a rebate is payable under such section, the amounts paid shall be the difference between (i) the payment amount under paragraph (3)(A)(ii)(I) of such section for such drug, and (ii) 20 percent of the inflation-adjusted payment amount under paragraph (3)(A)(ii)(II) of such section for such drug