Medicare Portability Rules: Original Medicare vs. Medicare Advantage

Understanding medicare portability rules starts with distinguishing between government-administered Medicare and private Medicare coverage. Original Medicare—consisting of Part A (Hospital Insurance) and Part B (Medical Insurance)—is a federal program with nationwide reach. If you carry Original Medicare, your physical location inside the United States or its territories does not restrict your access to care. You can move from Maine to Arizona, keep the exact same Medicare card, and see any doctor, specialist, or hospital that accepts Medicare assignment.

Original Medicare requires no primary care provider referrals, no regional network restrictions, and no plan changes simply because you changed your residential address. However, Original Medicare alone leaves significant financial gaps, such as deductibles, 20% coinsurance without an out-of-pocket maximum, and a complete absence of prescription drug coverage. Consequently, most retirees pair Original Medicare with supplemental coverage or opt instead for Medicare Advantage.

Medicare Advantage (Part C), offered by private insurance companies, operates under entirely different rules. Federal regulations require Medicare Advantage plans to maintain designated service areas, which insurance carriers usually define by county or group of counties. When you relocate outside your plan’s established medicare advantage service area, the insurance company cannot legally continue your coverage beyond emergency services.

For example, if you move from Cook County, Illinois, to Maricopa County, Arizona, your Illinois Medicare Advantage plan will no longer cover routine medical care once you establish residency in Arizona. Even if your insurance company offers Medicare Advantage plans in both states, individual plan structures, provider networks, copayments, and extra benefits vary widely by county. You must disenroll from your old regional plan and enroll in a plan available in your new county.