42 CFR §423.906

1. (a)Regular Federal matching. Regular Federal matching applies to the eligibility determination and notification activities specified in § 423.904(a) and (b).
2. (b)Medicare as primary payer. Medicare is the primary payer for covered drugs for Part D eligible individuals. Medical assistance is not available to full-benefit dual eligible individuals, including those not enrolled in a Part D plan, for—
   1. (1)Part D drugs; or
   2. (2)Any cost-sharing obligations under Part D relating to Part D drugs.
   3. (3)The effective date of paragraphs (b)(1) and (b)(2) of this section is January 1, 2006.
3. (c)Noncovered drugs. States may elect to provide coverage for outpatient drugs other than Part D drugs in the same manner as provided for non-full benefit dual eligible individuals or through an arrangement with a prescription drug plan or a MA-PD plan.