With the passage of the Balanced Budget Act of 1997, Medicare beneficiaries were formally given the option to receive their Original Medicare benefits through capitated health insurance Part C health plans, instead of through the Original fee for service Medicare payment system. Many had previously had that option via a series of demonstration projects that dated back to the early 1970s. These Part C plans were initially known in 1997 as "Medicare+Choice". As of the Medicare Modernization Act of 2003, most "Medicare+Choice" plans were re-branded as "Medicare Advantage" (MA) plans (though MA is a government term and might not even be "visible" to the Part C health plan beneficiary). Other plan types, such as 1876 Cost plans, are also available in limited areas of the country. Cost plans are not Medicare Advantage plans and are not capitated. Instead, beneficiaries keep their Original Medicare benefits while their sponsor administers their Part A and Part B benefits. The sponsor of a Part C plan could be an integrated health delivery system or spin-out, a union, a religious organization, an insurance company or other type of organization.

Public Part C Medicare Advantage and other Part C health plans are required to offer coverage that meets or exceeds the standards set by Original Medicare but they do not have to cover every benefit in the same way (the plan must be actuarially equivalent to Original Medicare benefits). After approval by the Centers for Medicare and Medicaid Services, if a Part C plan chooses to cover less than Original Medicare for some benefits, such as Skilled Nursing Facility care, the savings may be passed along to consumers by offering even lower co-payments for doctor visits (or any other plus or minus aggregation approved by CMS).

Original "fee-for-service" Medicare Parts A and B have a standard benefit package that covers medically necessary care as described in the sections above that members can receive from nearly any hospital or doctor in the country (if that doctor or hospital accepts Medicare). Original Medicare beneficiaries who choose to enroll in a Part C Medicare Advantage or other Part C health plan instead give up none of their rights as an Original Medicare beneficiary, receive the same standard benefits—as a minimum—as provided in Original Medicare, and get an annual out of pocket (OOP) upper spending limit not included in Original Medicare. However they must typically use only a select network of providers except in emergencies or for urgent care while travelling, typically restricted to the area surrounding their legal residence (which can vary from tens to over 100 miles depending on county). Most Part C plans are traditional health maintenance organizations (HMOs) that require the patient to have a primary care physician, though others are preferred provider organizations (which typically means the provider restrictions are not as confining as with an HMO). Others are hybrids of HMO and PPO called HMO-POS (for point of service) and a few public Part C health plans are actually fee for service hybrids.