For the first time, more than half of all people on Medicare are enrolled in a Medicare Advantage plan. According to data from the Centers for Medicare and Medicaid Services, approximately 34.4 million beneficiaries—representing about 54 percent of Medicare's total enrollment—were covered by Medicare Advantage as of early 2025. That figure is up from roughly 33 million and 53 percent a year earlier.
The growth is slower than in recent years—annual enrollment increased about 4 percent in 2025, compared with 6.5 percent between 2023 and 2024—but the milestone still represents a fundamental reorientation of how Americans receive their Medicare benefits.
What Medicare Advantage Is
Medicare Advantage, also called Medicare Part C, is an alternative to original Medicare offered by private insurance companies. Instead of receiving coverage directly from the federal government, beneficiaries enroll in a private plan—typically an HMO or PPO—that must cover everything original Medicare covers and often offers additional benefits like dental, vision, and hearing coverage.
Plans are paid a fixed amount per enrollee by the federal government and then manage the care of their members within that budget. Most plans charge little or no additional premium beyond the standard Part B premium, which makes them financially attractive to many retirees, particularly those without employer-sponsored retiree coverage.
Why Enrollment Keeps Rising
Several forces have pushed Medicare Advantage enrollment steadily higher for two decades. The additional benefits—particularly dental and vision, which original Medicare has never covered comprehensively—are a major draw. For many retirees, the chance to consolidate medical, drug, and supplemental coverage into a single card and a single premium is simply easier to manage.
Insurers have also invested heavily in marketing, and brokers often receive higher commissions for Advantage plan sales than for traditional Medicare supplement policies. Researchers and policymakers have noted that this creates incentives that may not always align with the beneficiary's best interests.
Much of the enrollment growth in 2025 came specifically from Special Needs Plans, or SNPs, which restrict enrollment to beneficiaries with specific chronic conditions or who are eligible for both Medicare and Medicaid. SNP enrollment has risen steadily since these plans became a permanent part of the program in 2018.
The Trade-offs Beneficiaries Should Understand
More beneficiaries means more scrutiny—and recent years have brought considerable attention to the ways Medicare Advantage plans differ from original Medicare in practice.
The most significant difference is network. Medicare Advantage plans typically require you to see doctors and hospitals within a defined network. If you travel frequently, spend time in two different states, or live in a rural area with limited provider participation, network restrictions can be a serious constraint. Original Medicare, by contrast, works with nearly any provider in the country who accepts Medicare.
Prior authorization is another area of meaningful difference. Medicare Advantage plans are permitted to require pre-approval for certain procedures, tests, and drugs. Regulators have increasingly focused on whether plans are using these requirements appropriately, and CMS has taken steps in recent years to require that any prior authorization criteria align with accepted clinical standards.
What the Shift Means for the Program Overall
As more beneficiaries move to Advantage plans, the nature of Medicare itself is changing. Original Medicare—the fee-for-service system—is increasingly serving as the coverage choice for sicker, older, and more complex patients, since those beneficiaries may be better served by the flexibility it provides. This dynamic affects how policymakers think about Medicare's finances and its long-term design.
The enrollment milestone also means that for many retirees entering Medicare for the first time, Advantage is no longer the alternative choice—it is simply the default expectation. That makes it more important than ever to understand what you are enrolling in, what the network looks like, and what options you have when care needs change.
Open enrollment runs from October 15 through December 7. The Medicare Plan Finder at medicare.gov allows side-by-side comparisons of plans in your area, including cost estimates based on your specific health needs and medications.