CMS has issued a final rule implementing amendments to the MSP provisions mandated by the MMA, effective March 24, 2008. Specifically, the rule clarifies the obligations of primary plans and payers, the nature of the insurance arrangements subject to the MSP rules, the circumstances under which Medicare may make conditional payments, and the obligations of primary payers to reimburse Medicare. The regulation finalizes a February 2006 interim final rule with comment period, with further clarifications regarding the reimbursement obligations and notice requirements of primary payers.