Medigap Guaranteed Issue Rights: When Insurers Must Sell You a Policy

Medigap — the private supplement insurance that fills Original Medicare's cost-sharing gaps — is not like other health insurance. Outside of specific guaranteed-issue windows, insurers in most states can reject your application, add waiting periods for pre-existing conditions, or charge dramatically higher premiums based on your health history. This guide explains every window when they cannot.

What "guaranteed issue" means

A guaranteed-issue right means an insurer selling Medigap in your state:

• Cannot deny your application
• Cannot impose a waiting period for pre-existing conditions
• Cannot charge you a higher premium because of your health history

Outside of a guaranteed-issue period, insurers in most states can reject applicants with conditions like heart disease, cancer, COPD, diabetes with complications, stroke history, or kidney disease. Rejection isn't arbitrary — insurers use standardized underwriting criteria — but the effect is the same: no coverage, or coverage only for conditions that don't matter.

Window 1: The Medigap Open Enrollment Period (6 months, federal, one-time)

Under federal law, your Medigap Open Enrollment Period (OEP) begins the first month you have both Medicare Part B coverage and are age 65 or older. It lasts 6 months and never comes around again.

During your OEP, an insurer must:

• Sell you any Medigap plan they offer in your state
• Accept your application without medical underwriting
• Charge you the same premium as a healthy applicant of the same age

When does the OEP clock start?

It depends on when you enroll in Part B, not necessarily your 65th birthday:

• If you enroll in Part B at 65 (typical): OEP starts the first day of your birthday month. If you turn 65 in September, your OEP runs September 1 through February 28.
• If you enrolled in Part B late (e.g., you had employer coverage until 67 and enrolled at retirement): your OEP starts when Part B becomes effective. This is a second OEP — but only because you were in a true special enrollment period. Someone who simply waited without qualifying coverage does not get a second bite.
• If you enrolled in Part B before 65 (due to disability): your OEP does not start until you turn 65, at which point you get a full 6-month OEP.

Window 2: Federal guaranteed-issue rights outside the OEP (63-day clock)

Beyond the OEP, federal law creates six specific situations where you have guaranteed-issue rights to buy a Medigap policy. For all six, you have 63 days from the date you lose your prior coverage (or the plan's termination date) to apply. Missing the 63-day window forfeits the right.

1. The Medicare Advantage 12-month trial right

This is the most commonly used federal GI situation. If you:

• Joined a Medicare Advantage plan when you first became eligible for Medicare (at 65 or at disability eligibility), and then decide within 12 months that MA isn't right for you —

— you have a federally guaranteed right to switch back to Original Medicare and buy any Medigap plan sold in your state. The 63-day clock starts when you disenroll from MA. This right applies once, for your first MA enrollment only.

2. Dropped Medigap to join Medicare Advantage (first time)

If you had a Medigap policy, dropped it to try MA for the first time, and then decide to switch back within 12 months, you have a guaranteed right to buy back at minimum the same Medigap plan you had before (or a plan with equal or lesser benefits).

3. Your Medicare Advantage or Medigap SELECT plan leaves your area

If the plan you're enrolled in loses its Medicare contract, stops operating in your service area, or is no longer offering coverage where you live, you have a guaranteed right to buy Medigap Plans A, B, C, F, K, or L. This covers both MA plans and Medigap SELECT (network-restricted Medigap) plans.

4. You move out of the plan's service area

If you relocate to an area where your current MA or SELECT plan doesn't operate, that move triggers guaranteed-issue rights for the same set of plans (A, B, C, F, K, L, plus the plan you had before, if applicable).

5. Your employer or union retiree coverage ends

If you've been relying on an employer- or union-sponsored plan that supplements Medicare and that coverage terminates — through the employer ending the program, your loss of eligibility, or the plan going bankrupt — you have a guaranteed right to buy Medigap Plans A, B, C, F, K, or L.

6. You lose Medicaid eligibility or a PACE program ends

Loss of Medicaid coverage that was supplementing Medicare, or loss of coverage through a Program of All-Inclusive Care for the Elderly (PACE), also triggers a guaranteed-issue right. This typically applies to retirees whose income rises above Medicaid thresholds after a period of low income.

Plans available under federal GI situations: Outside the OEP and the MA 12-month trial right, your guaranteed-issue options are generally limited to Plan A, B, C, F, K, or L — not Plan G or Plan N. Plan G and Plan N are available during your OEP or MA trial right, but the other situations above lock you into the legacy plan set. In practice, most people who need these guarantees will pursue either an OEP or the MA trial right.

Switching from Medicare Advantage to Medigap: what you can actually do

This is the most common regret scenario: someone chose MA at 65 (often for lower premiums), now has health problems or finds the network too restrictive, and wants to switch to Original Medicare + Medigap. Here are the realistic paths:

State-level protections beyond federal law

Several states go significantly further than federal minimum requirements. If you live in one of these states, your options are materially better.

Year-round guaranteed-issue states

Residents of New York and Connecticut have the most protection in the country. Both states require community rating and year-round guaranteed issue — insurers must sell you any Medigap plan at any time, with no underwriting. Premiums may vary by age band but not by health status.

Massachusetts uses standardized plans (Core and Supplement 1) and offers an annual open enrollment window from February 1 through March 31 each year, during which any resident can buy or switch Medigap without underwriting. Outside that annual window, insurers in Massachusetts may apply limited underwriting.

Maine also has enhanced guaranteed-issue protections that go beyond the federal floor — check with Maine's Bureau of Insurance for current rules.

Birthday rule states (as of April 2026)

Fourteen states currently have a "birthday rule" — a guaranteed-issue window each year around your birthday during which you can switch to a Medigap plan with equal or lesser benefits, without underwriting:

Important limitation of the birthday rule: It only lets you switch to a plan with equal or lesser benefits. You cannot use the birthday window to upgrade from Plan N to Plan G. You can use it to switch to the same plan with a cheaper insurer, which is its main practical use.

Coming soon: West Virginia's birthday rule takes effect June 11, 2026. New Mexico enacted a birthday rule in 2026 that takes effect in 2027.

What underwriting actually looks for (in states without GI protections)

If you're applying for Medigap outside a guaranteed-issue window in a state without special protections, expect insurers to ask about — and potentially decline for — conditions such as:

• Cancer (treated or untreated, within the past 2–10 years depending on carrier)
• Coronary artery disease, heart attack, or heart failure history
• Chronic obstructive pulmonary disease (COPD) or emphysema
• Insulin-dependent diabetes or diabetes with kidney, eye, or nerve complications
• Kidney disease or dialysis
• Stroke, TIA, or aneurysm history
• Organ transplant
• HIV/AIDS
• Alzheimer's or dementia

Carriers vary significantly. A condition that results in automatic denial at one insurer may be accepted (possibly with a waiting period) at another. Applying to multiple carriers simultaneously is legal and common. Working with an independent broker who knows multiple carriers' underwriting standards can matter a great deal.

The strategic implication: don't give up your OEP without a plan

Most people who end up locked out of Medigap made one of two mistakes:

1. Chose Medicare Advantage at 65 for lower premiums without understanding that switching back after 12 months would require underwriting. MA premium savings of $100–200/month over a few years can be more than offset by a lifetime of higher Medigap costs — or inability to get Medigap at all — if your health changes.
2. Enrolled in Part B late (correctly, under an employer coverage SEP) and assumed they'd just buy Medigap "when they need it" — without realizing the OEP window had already opened and would close.

If you're in your OEP window right now, the decision between MA and Original Medicare + Medigap is the most important Medicare decision you'll make. See our Medicare Advantage vs. Medigap comparison and Medigap Plan G vs. Plan N breakdown for the full analysis.

If you're past your OEP, look hard at state protections and the MA trial right. A fee-only Medicare advisor can map which guaranteed-issue windows still apply to your situation and which carriers in your state have the most favorable underwriting if GI isn't available.

Sources

1. Medicare.gov — When Can I Buy a Medigap Policy? Federal Medigap Open Enrollment Period: 6 months starting the first month you have Part B and are 65 or older. Guaranteed issue — insurer cannot deny, impose waiting period, or charge more for health history.
2. Medicare.gov — Can I Change My Medigap Policy? Federal guaranteed-issue situations outside OEP: MA trial right (12 months), MA/SELECT plan termination, move out of service area, employer/union coverage loss, Medicaid/PACE changes. 63-day clock from loss of prior coverage.
3. Boomer Benefits — Medigap Birthday Rule States State-by-state birthday rule details. As of 2026: CA, DE, ID, IL, IN, KY, LA, MD, NV, OK, OR, UT, VA, WY active. WV effective June 11, 2026; NM enacted 2026, takes effect 2027.
4. Medicare Interactive — Medigap Purchasing Details OEP tied to Part B effective date; separate OEP for beneficiaries who delay Part B with qualifying coverage; birthday rule scope limited to equal or lesser plans.
5. KFF — Medigap May Be Elusive for Beneficiaries with Pre-Existing Conditions Analysis of Medigap underwriting practices: common denial conditions, variability across states and carriers, impact of delayed enrollment.

Guaranteed-issue rules, OEP timing, and birthday-rule state data verified against Medicare.gov, CMS guidance, and state insurance department publications. State rules are subject to change — confirm current specifics with your state insurance commissioner. Values current as of April 2026.