Under the MSP statute, Medicare is the “secondary” payer of health benefits for Medicare beneficiaries when another entity is the “primary” payer of health benefits. Under new MSP enforcement rules, all entities that are considered primary payers under the MSP statute and that meet the definition of a responsible reporting entity (RRE) must register with CMS and comply with certain reporting requirements. In brief, such RREs include group health plans and non-group health plan arrangements, such as carriers of liability insurance (including self-insurance), no-fault insurance, and workers’ compensation. Registration for certain types of RREs (i.e., liability insurance (including self-insurance), no-fault insurance, and workers’ compensation) must be complete by September 30, 2009 and reporting must begin April 1, 2010. (Reporting for group health plan-type RREs is subject to a different timeline.) A Reed Smith Alert regarding the MSP registration and reporting requirements is available here.