If a letter arrived this year telling you that your Medicare Advantage plan is leaving your area, you are part of a growing wave of beneficiaries caught in a significant reshaping of the Medicare Advantage market. Carriers including Humana, Aetna, and a number of regional insurers have announced withdrawals from dozens of counties and several states over the past two plan years, citing a combination of higher-than-expected medical utilization and tighter federal reimbursement rates from the Centers for Medicare and Medicaid Services. The exits have accelerated compared to the relatively stable market of the early 2020s, and CMS data confirms that the number of counties losing at least one Medicare Advantage plan has risen sharply heading into 2026. For the roughly 33 million Americans enrolled in Medicare Advantage as of 2025, understanding what happens next — and acting within the right windows — is not optional. It is the difference between seamless coverage and a costly gap.
The financial mechanics driving these exits are worth understanding because they explain why rural and lower-income markets are being hit hardest. CMS has been recalibrating the risk adjustment model it uses to pay Medicare Advantage insurers, a technical change that reduced payments for plans that enrolled sicker-than-average populations. Simultaneously, post-pandemic utilization of outpatient surgery, physical therapy, and specialist visits has remained elevated, squeezing insurer margins well below projections. Several major carriers have publicly stated they are prioritizing profitability over market share in Medicare Advantage. That means more exits — particularly in counties where competition is thin and CMS benchmark payments are lower — are likely in coming years. Beneficiaries in rural areas should be especially proactive about understanding their backup options before a plan exit letter arrives, rather than after.
When your Medicare Advantage plan terminates coverage in your area, federal rules automatically trigger a Special Enrollment Period. This SEP typically gives you two full months to choose a new plan, beginning the month you receive written notice that your plan is leaving. During this window you can enroll in any Medicare Advantage plan available in your county, or you can return to Original Medicare Parts A and B. You do not have to wait for the Annual Enrollment Period, which runs October 15 through December 7 each year. Letting this SEP lapse without acting is a serious mistake. If you miss it, you could face a gap in coverage or be automatically defaulted into a plan selected by CMS that may not include your doctors, your pharmacy, or your current medications at the same cost tier.
One of the most valuable — and least publicized — rights triggered by a plan exit is your potential eligibility for guaranteed-issue Medigap enrollment. Under federal law, when your Medicare Advantage plan involuntarily terminates your coverage, you have the right to purchase a Medigap policy without going through medical underwriting. That means the insurer cannot reject you or charge you higher premiums based on pre-existing conditions such as diabetes, heart disease, COPD, or a history of cancer. This guaranteed-issue right typically lasts 63 days from the date your Medicare Advantage coverage ends — not from the date you receive the notice, but from the actual termination date. Mark that deadline on your calendar the day the letter arrives. Medigap plans, labeled Plan G, Plan N, Plan K, and others, work alongside Original Medicare to cover costs like the Part A hospital deductible, which is $1,676 per benefit period in 2025, coinsurance, and in some cases Part B excess charges. Plan G is currently the most comprehensive option available to new Medicare enrollees and typically covers everything except the Part B deductible, which is $257 in 2025. For beneficiaries who have previously been denied Medigap coverage due to health conditions, a plan exit may be the rare second chance to obtain the supplemental protection they need.
Not every replacement Medicare Advantage plan is equal, and the differences in what you actually pay can be dramatic. In 2025, the average Medicare Advantage plan premium was approximately $17 per month nationally, but many plans in competitive urban markets carried $0 premiums, while plans in rural counties with fewer competing insurers sometimes ran $50 to $100 per month or more. The annual out-of-pocket maximum — the most you would pay in a calendar year for covered in-network services — ranged from under $3,000 on some plans to the federal cap of $9,350 for in-network services in 2025. Choosing a plan based on the monthly premium alone, without checking the out-of-pocket maximum, is one of the most common and costly errors beneficiaries make. A $0-premium plan with a $9,000 out-of-pocket maximum can cost you far more in a year of moderate health needs than a $60-per-month plan with a $3,500 cap.
Your prescription drug coverage deserves equal scrutiny during any plan switch. If you are enrolled in a Medicare Advantage plan that includes Part D drug coverage — called an MA-PD plan — switching plans means your new plan will almost certainly have a different formulary, the list of covered drugs and their cost tiers. A medication that cost you $10 per month under your old plan could cost $80 or more under a new plan if it falls on a higher tier, or it may not be covered at all, requiring a prior authorization or exception request. Before you enroll in any replacement plan, go to Medicare.gov and use the Plan Finder tool. Enter your specific medications, exact dosages, and your preferred pharmacy — including whether you use mail order — to see your estimated annual drug costs under each plan you are considering. This single step can reveal differences of $500 to $2,000 or more per year between plans that look similar on the surface.
Provider network disruptions are the other major financial and medical risk when plans exit. Medicare Advantage plans use defined networks of doctors, hospitals, and specialists, and those network contracts do not transfer when you switch insurers. Your primary care physician, cardiologist, orthopedic surgeon, or oncologist may not participate in the replacement plan you are considering. Before you enroll, call your most important providers directly and ask whether they are contracted with the specific plan — not just the insurer's brand, but the specific plan name and ID number — because the same insurer can have multiple plans in a county with different networks. Do not rely solely on the insurer's online provider directory, which CMS audits have repeatedly found to contain outdated or inaccurate information. If you are in active treatment for a serious condition such as cancer, heart failure, or following a recent surgery, continuity of care is a medical necessity, and a network mismatch can force you to either pay out-of-network rates or change providers mid-treatment.
For beneficiaries who decide that returning to Original Medicare is the right move after a plan exit, the transition requires a few additional steps that are easy to overlook. Original Medicare does not include prescription drug coverage, so you will need to separately enroll in a standalone Part D Prescription Drug Plan. In 2025, standalone Part D premiums ranged from roughly $5 to over $100 per month depending on the plan and your county, with the national base beneficiary premium set at $36.78. You will also want to seriously evaluate Medigap coverage to protect yourself from Original Medicare's cost-sharing structure, which has no annual out-of-pocket maximum on its own. Without a Medigap policy, a serious hospitalization under Original Medicare could expose you to the $1,676 Part A deductible per benefit period — and if you are hospitalized more than once in a year, that deductible applies each time — plus 20 percent coinsurance for all Part B services with no cap on your total liability.
State-level protections can meaningfully expand your options, particularly if you are considering Medigap. Thirteen states have enacted birthday rules or continuous open enrollment protections that give Medigap enrollees additional windows to switch policies without medical underwriting, independent of any plan exit. 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, you may have more flexibility to shop for a better Medigap plan even outside the 63-day guaranteed-issue window triggered by a plan exit. New York and Massachusetts go further, requiring Medigap insurers to accept all applicants year-round regardless of health status, which means residents of those states have a permanent safety net that most Americans do not. If you are in any of these states, contact your State Health Insurance Assistance Program counselor to understand exactly which protections apply to your situation and timeline.
SHIP counselors — available free of charge in every state — are trained volunteers with no financial stake in your decision, which makes them a fundamentally different resource than an insurance agent or broker who earns a commission on enrollment. A SHIP counselor can walk you through a side-by-side plan comparison, explain your Medigap rights in plain language, and help you evaluate whether Original Medicare with a standalone Part D plan or a new Medicare Advantage plan better fits your health situation and budget. Finding your local SHIP office takes less than two minutes at shiphelp.org. You can also call 1-800-MEDICARE, which is 1-800-633-4227, for direct CMS assistance available 24 hours a day, seven days a week. Given that the wrong plan choice can cost you thousands of dollars in a single year of moderate health needs, spending an hour with a SHIP counselor before you enroll is among the highest-value uses of your time during this transition.
The structural pressure driving insurer exits is not going away, and the beneficiaries most at risk are those in rural counties, lower-income markets, and areas where only one or two Medicare Advantage plans have ever competed. If you live in one of these areas and currently have Medicare Advantage coverage, it is worth taking stock of your backup options now — before a plan exit letter forces the decision under time pressure. Review what Medigap plans are available and what they cost in your area today, check whether your county has at least two or three Medicare Advantage alternatives, and make sure your doctors accept Original Medicare as a fallback. The beneficiaries who navigate plan exits most successfully are not the ones who react fastest — they are the ones who already understood their options before the letter arrived.