Medicare Advantage is a private insurance alternative to Original Medicare. Officially called Part C, these plans are sold by private insurance companies but approved and regulated by the federal government. They bundle your Part A (hospital) and Part B (medical) coverage into a single plan, and most also include Part D prescription drug coverage. More than half of all Medicare beneficiaries, about 34.1 million people, are now enrolled in Medicare Advantage rather than Original Medicare.
How Medicare Advantage Works
When you enroll in a Medicare Advantage plan, you still have Medicare. You continue paying your monthly Part B premium to the government. But instead of the government paying your doctors and hospitals directly (as it does with Original Medicare), it pays a fixed monthly amount per enrollee to the private insurance company running your plan. That company then manages your care and handles your claims.
The amount the government pays each insurer is tied to a benchmark based on what traditional Medicare spends per beneficiary in your county. Insurers submit bids estimating what it will cost them to cover standard Medicare services, plus their administrative expenses and profit. If a plan bids below the benchmark, it receives a rebate, a portion of the savings, which it must put toward extra benefits for members or lower premiums. If a plan bids above the benchmark, you pay the difference as an additional monthly premium.
Every Medicare Advantage plan is required by law to cover everything Original Medicare covers. You cannot lose access to a Medicare-covered service simply by choosing an Advantage plan. What changes is how that coverage is delivered: which doctors and hospitals you can use, what approvals are needed, and what you pay out of pocket at the point of care.
Extra Benefits Beyond Original Medicare
The biggest draw for many enrollees is that Medicare Advantage plans often include benefits Original Medicare does not cover at all. The most common extras are dental care, vision exams and eyeglasses, and hearing aids. Many plans also offer fitness memberships, meal delivery after a hospital stay, and transportation to medical appointments. These supplemental benefits vary widely from plan to plan, so the extras available to you depend on where you live and which plan you choose.
Most Medicare Advantage plans bundle prescription drug coverage directly into the plan (these are called MA-PD plans). If your plan includes drug coverage, you must use it. You cannot buy a separate standalone Part D plan on the side. Some Advantage plans don’t include drug coverage at all, and if yours is one of them, you still cannot enroll in a separate drug plan. This is an important limitation to understand before enrolling.
Types of Medicare Advantage Plans
Medicare Advantage plans come in several structures, each with different rules about which providers you can see.
- HMO (Health Maintenance Organization): You generally must use doctors and hospitals inside the plan’s network, except for emergencies or urgent care. You need a referral from your primary care doctor to see a specialist.
- PPO (Preferred Provider Organization): You can see any provider in or out of network, but you pay less when you stay in network. No referrals are needed for specialists.
- PFFS (Private Fee-for-Service): You can visit any Medicare-approved provider who accepts the plan’s payment terms. No referrals required, but not every provider will agree to treat you under these plans.
- SNP (Special Needs Plan): Designed for people with specific chronic conditions, those who qualify for both Medicare and Medicaid, or residents of certain institutions. Network and referral rules depend on whether the SNP is structured as an HMO or PPO.
HMOs and PPOs make up the vast majority of Medicare Advantage enrollment. The choice between them usually comes down to whether you value lower costs (HMOs are typically cheaper) or flexibility in choosing providers (PPOs let you go out of network).
Costs and Financial Protections
You always pay your standard Part B premium regardless of which Medicare Advantage plan you choose. On top of that, many plans charge their own monthly premium, though some advertise a $0 plan premium. A few plans even help cover part of your Part B premium. Lower-premium plans typically have higher copays and deductibles at the point of care, so the total cost picture matters more than any single number.
One of the most significant financial differences from Original Medicare is the annual out-of-pocket maximum. Original Medicare has no cap on what you can spend in a year, meaning a serious illness could result in unlimited costs unless you carry supplemental Medigap insurance. Medicare Advantage plans are required to cap your yearly spending. In 2025, that limit cannot exceed $9,350 for in-network services or $14,000 for in-network and out-of-network services combined. Once you hit your plan’s limit, covered services cost you nothing for the rest of the year.
Trade-Offs Compared to Original Medicare
The core trade-off is straightforward: Medicare Advantage typically offers lower costs and extra benefits in exchange for less freedom in choosing your doctors and more administrative requirements.
With Original Medicare, you can see any doctor or hospital in the country that accepts Medicare, no referrals, no network restrictions, no pre-approvals. With most Advantage plans, you are limited to a network of providers, at least if you want the lowest out-of-pocket costs. If your preferred specialist is out of network, you may pay significantly more or not be covered at all, depending on the plan type.
Prior authorization is another key difference. Medicare Advantage plans typically require you to get approval from the plan before certain services, tests, or procedures are covered. This can mean waiting for the plan to review and approve a treatment your doctor has recommended. Original Medicare rarely requires this step. For people with complex health needs who see multiple specialists, prior authorization requirements can add friction and delays to their care.
On the other hand, Original Medicare leaves you exposed to potentially unlimited out-of-pocket costs unless you purchase a Medigap supplemental policy, which adds its own premium. Medicare Advantage builds that spending cap into the plan, and bundling dental, vision, and drug coverage into one card simplifies the experience for many people.
Star Ratings and Plan Quality
Every Medicare Advantage plan receives a quality rating from CMS on a scale of one to five stars. These ratings are based on up to 43 measures covering clinical quality, member satisfaction, and plan administration. The measures range from how well the plan manages diabetes and blood pressure to how quickly members can get appointments, how often members choose to leave the plan, and how the plan handles appeals.
Star ratings matter beyond bragging rights. Plans with higher ratings receive larger rebates from the government, which means more money to spend on extra benefits or lower premiums. A plan rated 4.5 stars or above keeps 70% of the difference between its bid and the benchmark, while a plan below 3.5 stars keeps only 50%. You can check any plan’s star rating on Medicare.gov before enrolling.
When and How to Enroll
Most people first become eligible to join a Medicare Advantage plan during their Initial Enrollment Period, the seven-month window surrounding their 65th birthday. After that, the main opportunity to join, switch, or drop a plan is the Annual Enrollment Period, which runs from October 15 through December 7 each year. Changes made during this window take effect on January 1.
If you’re already in a Medicare Advantage plan and want to make a change after open enrollment, you have one more window: the Medicare Advantage Open Enrollment Period from January 1 through March 31. During this time, you can switch to a different Advantage plan or drop your plan entirely and return to Original Medicare (and join a standalone Part D drug plan if needed). You cannot use this period to move from Original Medicare into an Advantage plan.
Medicare Advantage enrollment has grown dramatically over the past two decades, rising from 19% of eligible beneficiaries in 2007 to 54% in 2025. That growth reflects both the appeal of extra benefits and spending caps and the aggressive marketing of these plans. Whether an Advantage plan is the right fit depends on your health needs, your preferred doctors, and how you weigh cost savings against provider flexibility.