Subsection (a) shall apply to covered part D drugs dispensed under this part on or after January 1, 2011.
42 U.S. Code § 1395w–153 - Condition for coverage of drugs under this part
(a) In generalIn order for coverage to be available under this part for covered part D drugs (as defined in section 1395w–102(e) of this title) of a manufacturer, the manufacturer must—
participate in the Medicare coverage gap discount program under section 1395w–114a of this title;
have entered into and have in effect an agreement described in subsection (b) of such section with the Secretary; and
(b) Effective date
(c) Authorizing coverage for drugs not covered under agreementsSubsection (a) shall not apply to the dispensing of a covered part D drug if—
the Secretary has made a determination that the availability of the drug is essential to the health of beneficiaries under this part; or
(d) Definition of manufacturer
 So in original. Probably should be followed by “ending on”.