Advantage plans generally use a network of doctors and hospitals, similar to employer health insurance. Depending on the plan type, going outside that network can cost more or not be covered at all, and some plans require a referral from a primary care doctor before you can see a specialist.
Original Medicare, by contrast, is accepted by the vast majority of doctors and hospitals nationwide with no network or referral requirement. If you split time between states, or you're attached to a specific specialist, confirm they're in-network before you enroll — don't assume.
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