Medigap Coverage Can Be Hard to Get If You Have Pre-Existing Conditions

For millions of people turning 65 and enrolling in Medicare, Medigap — also called Medicare Supplement Insurance — sounds like the obvious solution to Original Medicare's significant cost-sharing gaps. Original Medicare leaves beneficiaries responsible for a $1,676 Part A deductible per benefit period in 2025, a $257 Part B deductible, and 20% coinsurance on most outpatient services with no out-of-pocket maximum. A Medigap plan is designed to cover most or all of those costs. But there's a catch that catches too many people off guard: your right to actually buy one of these plans, regardless of your health, is far more limited than most people realize.

Federal law gives every new Medicare beneficiary a one-time, six-month open enrollment window that begins the month your Part B coverage starts. During this window, insurers selling Medigap plans in your state must sell you any plan they offer at standard rates — they cannot ask about your health history, deny your application, or charge you more because of a pre-existing condition. This is called your guaranteed issue right, and it is the most powerful consumer protection in the Medigap market. Once that six-month window closes, however, federal law largely steps back. In most states, insurers are legally permitted to use medical underwriting — meaning they can review your health history, ask detailed questions about your conditions and medications, and either deny your application outright or charge you a higher premium based on what they find.

The conditions that commonly trigger denials or surcharges are not rare or exotic. According to research from KFF (formerly the Kaiser Family Foundation), insurers frequently flag diabetes, heart disease, chronic obstructive pulmonary disease (COPD), stroke history, kidney disease, and even a history of cancer treatment. Some insurers apply waiting periods of up to six months before covering conditions that existed before your policy started. Others simply decline applicants with certain diagnoses entirely. This means a 68-year-old who delayed enrolling in Part B while working, or a 72-year-old who dropped a Medigap plan during a financially tight year and now wants to re-enroll, may find the door effectively closed — not because of anything they did wrong, but because of the health conditions that come with aging.

The financial stakes of being locked out of Medigap are substantial. Without a supplement plan, a serious illness or hospitalization can expose a Medicare beneficiary to costs that accumulate quickly. A 60-day hospital stay, for example, would leave someone on Original Medicare alone responsible for the $1,676 Part A deductible plus $419 per day in coinsurance for days 61 through 90 in 2025. A cancer diagnosis requiring ongoing chemotherapy could mean 20% coinsurance on every infusion, every specialist visit, and every imaging scan — with no cap on total out-of-pocket spending under Original Medicare. This is precisely the population — people with serious, ongoing health conditions — who most need the financial protection Medigap provides, and yet they are the people most likely to be denied it.

State-level protections vary enormously, and where you live can make a significant difference in your options. A small number of states have enacted laws that go beyond federal minimums. New York and Massachusetts, for instance, require insurers to offer Medigap plans on a guaranteed issue basis year-round, regardless of health status — though premiums in those states tend to be higher as a result. Connecticut and Maine also have stronger-than-average protections. Beyond those states, thirteen states have adopted what's known as the birthday rule, which gives beneficiaries a 30-day window each year around their birthday to switch to a Medigap plan with equal or lesser benefits without medical 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 and currently have a Medigap plan, your birthday window may allow you to switch to a different plan — potentially one with lower premiums — without risking your coverage by going through underwriting.

For beneficiaries who missed their initial enrollment window and do not live in a state with expanded protections, there are still a few federally guaranteed situations that restore your right to buy Medigap without underwriting. These are called Special Enrollment Periods or guaranteed issue rights, and they apply in specific circumstances: if your Medicare Advantage plan leaves your service area or loses its Medicare contract, if you move out of your plan's service area, if you enrolled in Medicare Advantage when you first became eligible and are now switching back to Original Medicare within the first year, or if your employer-sponsored retiree coverage ends. These windows are typically 63 days long, and they are strict — missing the deadline means losing the protection. If you think you may qualify for one of these situations, contacting your State Health Insurance Assistance Program (SHIP) counselor is one of the most practical steps you can take. SHIP counselors provide free, unbiased guidance and can help you identify which rights apply to your situation.

For people who genuinely cannot qualify for Medigap due to health conditions and do not have access to a guaranteed issue window, Medicare Advantage plans represent the main alternative for managing cost exposure. Medicare Advantage plans are required by law to accept any Medicare beneficiary during the Annual Enrollment Period (October 15 through December 7) and the Open Enrollment Period (January 1 through March 31) regardless of health status. In 2025, many Medicare Advantage plans carry $0 monthly premiums and include an annual out-of-pocket maximum — the average out-of-pocket limit across plans nationally has been around $5,000 to $8,000 for in-network services, though this varies widely by plan and region. The trade-off is that Medicare Advantage plans use networks, require referrals in some cases, and can change their benefits, premiums, and formularies each year. They are not a perfect substitute for Medigap, but for someone who cannot pass medical underwriting, they may provide meaningful financial protection that Original Medicare alone does not.

One expensive mistake worth highlighting: some beneficiaries drop a Medigap plan they already have — perhaps because the premium increased and a Medicare Advantage plan looked more attractive — without fully understanding that they may not be able to get back into Medigap later. If you currently have a Medigap plan and are considering dropping it, think carefully about your long-term health trajectory. Premiums for Medigap plans do increase with age and can feel burdensome, but the guaranteed coverage they provide becomes more valuable, not less, as health conditions develop. Switching to Medicare Advantage to save on premiums is a legitimate choice, but it should be made with clear eyes about what you may be giving up permanently.

If you are approaching 65 or are newly enrolled in Medicare Part B, the single most important action you can take is to use your six-month guaranteed issue window deliberately. Compare Medigap plans — Plan G is currently the most comprehensive plan available to new enrollees (Plan F was discontinued for those newly eligible after January 1, 2020), and Plan N offers lower premiums in exchange for copays on some visits. Get quotes from multiple insurers, because premiums for the same standardized plan can vary by hundreds of dollars per year depending on the company. And if you have questions about your specific rights based on your state or circumstances, reach out to your state's SHIP program — find your local counselor at shiphelp.org — or call 1-800-MEDICARE. The window to act without health consequences is real, but it does not stay open long.