Medigap Coverage Can Be Denied If You Have Pre-Existing Conditions

For millions of Medicare beneficiaries, the assumption that health coverage gets easier after 65 runs into a hard wall when they try to buy a Medigap policy. Unlike Medicare Advantage plans, which are required by federal law to accept any Medicare beneficiary regardless of health status during open enrollment, Medigap — also called Medicare Supplement Insurance — operates under a very different set of rules in most of the country. In the majority of states, private insurers selling Medigap plans can review your medical history, reject your application outright, or charge you substantially higher premiums if you have pre-existing conditions like heart disease, diabetes, COPD, or a history of cancer. This is not a loophole or an oversight. It is the standard legal framework governing Medigap in 37 states, and it catches many beneficiaries off guard at exactly the moment they need coverage most.

The core issue is that federal law only guarantees your right to buy a Medigap policy — without medical underwriting — during specific, time-limited windows. The most important of these is the Medigap Open Enrollment Period, a six-month window that begins on the first day of the month in which you are both age 65 or older and enrolled in Medicare Part B. During this window, no insurer can deny you a Medigap policy, charge you more because of your health, or make you wait for coverage of a pre-existing condition. This is your single strongest federal protection, and it does not repeat. Once that six-month window closes, you generally lose the automatic right to buy Medigap at standard rates, and insurers can begin applying medical underwriting to your application.

What this means in practice is that timing your Medicare enrollment decisions is not just administrative — it is a financial health decision with potentially lasting consequences. A 65-year-old who delays enrolling in Part B because they are still covered by an employer plan, for example, gets a new six-month Medigap open enrollment window when they eventually do enroll in Part B, regardless of age. But a 70-year-old who has been on Medicare Advantage and wants to switch to Original Medicare plus a Medigap plan faces a very different situation. In most states, that person can be turned down or charged more based on any number of health conditions that have developed over those five years. The insurer may ask about hospitalizations, surgeries, diagnoses, and medications going back two to ten years depending on the state and the insurer's underwriting guidelines.

The standardized Medigap plans — labeled Plan A through Plan N in 2026 — are sold by private insurers but their benefits are set by federal law, meaning a Plan G from one company covers the same services as a Plan G from another. What differs is the premium, and medical underwriting can dramatically affect what you are quoted. Plan G, which is currently one of the most popular options for new enrollees since Plan F was closed to those who became Medicare-eligible after January 1, 2020, typically covers the Part A deductible ($1,676 in 2026), the Part B coinsurance, skilled nursing facility coinsurance, and foreign travel emergency care, among other costs. The Part B deductible ($257 in 2026) is not covered by Plan G, which is one distinction from the now-closed Plan F. Plan N covers similar benefits but requires copayments of up to $20 for some office visits and up to $50 for emergency room visits that do not result in inpatient admission. These cost-sharing differences matter when you are comparing premiums, because a lower-premium Plan N may still make financial sense if you are relatively healthy and do not visit specialists frequently.

Beyond the initial open enrollment window, federal law provides guaranteed issue rights in a handful of other specific situations. If your Medicare Advantage plan leaves your area or stops covering your county, you have a guaranteed right to buy certain Medigap plans. If you move out of your plan's service area, the same protection applies. If you enrolled in a Medicare Advantage plan for the first time and decide within the first year that you want to return to Original Medicare, you have a trial right that allows you to buy a Medigap policy without underwriting. These are narrow windows — typically 63 days from the triggering event — and they apply to specific plan types, not all Medigap policies. Missing these deadlines by even a few days can eliminate the protection entirely.

Thirteen states have gone beyond federal minimums to provide additional protections. California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon all have what is commonly called a birthday rule or similar guaranteed issue provision. In these states, beneficiaries typically have a 30-day window around their birthday each year during which they can switch to a Medigap plan with equal or lesser benefits from a different insurer without medical underwriting. This is a meaningful protection because it allows people who are aging and developing new health conditions to shop for better premiums or switch insurers without fear of being denied. New York and Connecticut go further, requiring insurers to sell Medigap policies to Medicare beneficiaries of any age on a guaranteed issue basis year-round — making those states among the most protective in the country for people with chronic conditions. If you live in one of these states, your options are meaningfully broader than what federal law alone provides.

For beneficiaries in the 37 states without these additional protections, the practical guidance is to treat the Medigap open enrollment window as a one-time opportunity that should not be wasted. If you are approaching 65 and have any chronic health conditions — or even a family history that might concern an underwriter — enrolling in a Medigap plan during that initial six-month window is typically the most cost-effective path. Waiting to see how your health develops, or assuming you can always switch later, is a gamble that many beneficiaries lose. Insurers in these states are not required to tell you that you are being underwritten or explain why you were denied; they simply issue a denial or a higher-rated premium quote.

The premium variation that underwriting produces can be substantial. A 68-year-old with well-controlled Type 2 diabetes and a history of atrial fibrillation might be quoted $180 per month for Plan G in a state with medical underwriting, while a healthier peer of the same age might pay $130 per month for identical coverage. In some cases, applicants with more serious conditions — recent cancer treatment, heart surgery, or kidney disease — may be denied entirely and have no Medigap option available to them outside of a guaranteed issue window. These individuals are not without options: Medicare Advantage plans must accept them during the Annual Enrollment Period (October 15 through December 7 each year) and the Open Enrollment Period (January 1 through March 31), but Advantage plans come with network restrictions, prior authorization requirements, and cost-sharing structures that differ significantly from Original Medicare plus Medigap.

One underappreciated aspect of this issue is how it affects people who are under 65 and on Medicare due to disability. Federal law does not require states to offer Medigap open enrollment rights to disabled Medicare beneficiaries under 65, though about 30 states have chosen to extend some protections to this group. The rules vary widely — some states require insurers to offer at least one Medigap plan to under-65 beneficiaries, while others allow full medical underwriting or charge significantly higher premiums. A 58-year-old on Medicare due to a disability who tries to buy a Medigap plan in a state without these protections may find the market effectively closed to them until they turn 65 and gain federal guaranteed issue rights.

If you are currently on Medicare Advantage and considering a switch to Original Medicare with a Medigap supplement, the most important first step is to check whether you are within a guaranteed issue window before you disenroll from your Advantage plan. Disenrolling first and then discovering you cannot get Medigap coverage at standard rates — or at all — leaves you in a difficult position. Your State Health Insurance Assistance Program, known as SHIP, offers free one-on-one counseling from trained advisors who can walk through your specific situation, review your health history in the context of your state's rules, and help you understand which plans you are likely to qualify for. SHIP counselors are available in every state and do not sell insurance, which means their guidance is unbiased. You can find your local SHIP contact through Medicare.gov or by calling 1-800-MEDICARE.

The broader policy picture is that Medigap's underwriting rules represent one of the most significant gaps in Medicare's consumer protections, and it is one that disproportionately affects people who need supplemental coverage the most. Advocacy organizations and some members of Congress have periodically raised the idea of requiring guaranteed issue for Medigap on a broader basis, similar to the Affordable Care Act's rules for individual market insurance. As of 2026, no such federal requirement has been enacted, which means the state-by-state patchwork of protections remains the reality for most beneficiaries. Understanding where your state stands — and acting during the windows when you do have guaranteed rights — remains the most reliable way to secure the supplemental coverage that makes Medicare work as a complete health insurance system.