CMS Eyes Auto-Enrollment Into Medicare Advantage: What It Means for You

A proposal being considered at the Centers for Medicare & Medicaid Services would allow — or potentially require — new Medicare beneficiaries to be automatically enrolled into Medicare Advantage plans rather than defaulting into Original Medicare (Parts A and B). While the idea is still in the discussion phase as of mid-2026, it represents one of the most consequential structural changes to Medicare enrollment in the program's 60-year history, and every beneficiary approaching 65 or currently enrolled needs to understand what's at stake.

Right now, when you turn 65 and qualify for Medicare, the default is Original Medicare — the federal fee-for-service program administered directly by CMS. You receive your red, white, and blue Medicare card, and you can see any doctor or hospital in the country that accepts Medicare, which is the vast majority of providers. From that baseline, you can choose to add a standalone Part D drug plan (premiums average around $40–$50 per month in 2025), purchase a Medigap supplemental policy to cover cost-sharing, or opt into a Medicare Advantage plan instead. The key word is 'choose.' Auto-enrollment would flip that default, meaning inaction — not making an active decision — could land you inside a private insurance plan with its own network, prior authorization rules, and cost structures.

Medicare Advantage plans, offered by private insurers under contract with CMS, now cover more than 54% of all Medicare beneficiaries — roughly 33 million people as of 2025, according to KFF. Many enrollees are satisfied, particularly those who value the $0 premium options (available in many counties), bundled drug coverage, and extras like dental, vision, and hearing benefits that Original Medicare doesn't cover. In 2025, the average MA enrollee had access to plans with a maximum out-of-pocket cap of around $4,500 to $8,850 for in-network services, depending on plan type. These caps don't exist in Original Medicare without a Medigap policy, which is a genuine advantage for people who want predictable costs.

But Medicare Advantage is not universally better, and that's precisely why the auto-enrollment debate is so charged. MA plans operate through provider networks — HMOs require referrals and restrict you to in-network doctors, while PPOs offer more flexibility but at higher cost-sharing for out-of-network care. Prior authorization — where the insurer must approve certain procedures, specialist visits, or hospital stays before they happen — is a standard feature of MA plans and has been the subject of significant federal scrutiny. A 2022 HHS Office of Inspector General report found that MA plans denied 13% of prior authorization requests that would likely have been covered under Original Medicare. For a new beneficiary who doesn't know they've been auto-enrolled, discovering these restrictions at the moment of a health crisis is a serious problem.

The Medigap complication is one of the most underappreciated risks in any auto-enrollment scenario. When you first enroll in Medicare Part B, you have a six-month guaranteed issue window to purchase any Medigap policy in your state without medical underwriting — meaning insurers cannot deny you coverage or charge you more based on pre-existing conditions. This window is tied to your Part B enrollment date, not to whether you're in Original Medicare or MA. However, if you're auto-enrolled into an MA plan and later want to switch to Original Medicare and add a Medigap policy, you lose that guaranteed issue protection in most states. Insurers can then review your health history and potentially deny coverage or charge significantly higher premiums. Plan F, the most comprehensive Medigap option (available to those who became eligible before January 1, 2020), can run $150–$300 per month depending on your age and state — but only if you can get it. Plan G, the current gold-standard option for newer enrollees, typically runs $100–$250 per month and covers everything except the Part B deductible ($257 in 2025).

There are 13 states that offer what's known as the 'birthday rule' — a guaranteed issue window that opens annually around your birthday, allowing you to switch Medigap plans without underwriting. Those states are California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon. If you live in one of these states, the long-term risk of being auto-enrolled into MA and later wanting to switch is somewhat lower, because you'd have an annual opportunity to obtain Medigap coverage. But in the remaining 37 states, once your initial enrollment window closes, your health history becomes a gating factor for Medigap access — and that's a permanent consequence of a temporary default.

The policy mechanics of how auto-enrollment would actually work remain unclear, and that ambiguity is part of what makes this proposal so important to watch. Would CMS auto-enroll beneficiaries into the highest-rated plan in their county? The lowest-premium plan? A plan selected by a regional contractor? Would low-income beneficiaries who qualify for both Medicare and Medicaid (dual-eligibles) be treated differently? Currently, dual-eligible beneficiaries can be auto-enrolled into D-SNPs (Dual Eligible Special Needs Plans), a type of MA plan designed specifically for their needs — so some form of auto-enrollment already exists in limited contexts. Expanding that model to the broader Medicare population raises entirely different equity and access questions.

If you're currently enrolled in Medicare and happy with your coverage, this proposal doesn't affect you immediately. But if you have children or grandchildren approaching 65, or if you're in that window yourself, the practical advice is this: do not let Medicare enrollment happen passively. During your Initial Enrollment Period — which spans seven months, beginning three months before the month you turn 65 and ending three months after — actively evaluate whether Original Medicare plus Medigap or a Medicare Advantage plan better fits your health needs, your doctors, and your financial situation. Use the Medicare Plan Finder at Medicare.gov to compare actual plans available in your ZIP code. Check whether your current doctors are in-network for any MA plan you're considering, and call those doctors' offices directly to confirm — plan directories are not always current.

For beneficiaries who want to weigh in on this proposal, CMS accepts public comments during formal rulemaking periods, which are announced in the Federal Register. AARP and the Medicare Rights Center both track these comment periods and provide plain-language summaries at aarp.org and medicarerights.org respectively. The distinction between being assigned to a plan and choosing one may sound bureaucratic, but in Medicare, that difference can determine whether you can see your oncologist, whether your hip replacement gets approved on time, and whether you can afford supplemental coverage for the rest of your life.