Prior to the 2019 plan year, physicians who are providing services to Medicare Advantage (MA) enrollees are required to enroll as Medicare providers. Currently, healthcare providers are not required to be enrolled in Medicare in order to bill for services provided to MA enrollees, whether those services are covered under the standard or a supplemental MA benefit. However, CMS issued a Final Rule on Nov. 15, 2016, that will require network or contracted providers to be enrolled as Medicare providers starting in 2019, even if the services delivered are covered only under an MA supplemental benefit. 81 Fed. Reg. 80170, 80445. There are other circumstances in which providers must be enrolled in Medicare as of 2019, for example, if providers or suppliers are considered first-tier, downstream and related entities of the MA organization, or participating in a demonstration or pilot program.

The Final Rule confirms that health care providers and suppliers as defined by the Social Security Act (SSA) "may" enroll in Medicare if they meet the proper screening and enrollment requirements. However, the Final Rule requires Medicare provider enrollment starting in 2019, and codifies this requirement at 42 C.F.R. § 422.222. Several commenters asked in the Final Rule whether providers are required to enroll in Medicare if they are providing supplemental services under MA, such as routine eye care services, dental benefits and wellness programs. CMS clarifies that they "expect all providers and suppliers that are categorically-eligible to enroll in Medicare… to enroll in Medicare if they wish to participate in the MA program. This includes providers and suppliers of dental, eye care and other supplemental services." This rule corresponds with a requirement, which also takes effect on Jan. 1, 2019, that any physician or other eligible professional who prescribes Medicare Part D drugs must either enroll in Medicare or opt out in order to prescribe drugs to their Part D patients.