Your Medigap Open Enrollment Period is a one-time six-month window starting the first month you are 65 and enrolled in Part B, when insurers must sell you any supplement plan regardless of health. This guide explains exactly when it opens, why it is not the same as Medicare's fall open enrollment, and the four narrower paths that remain if you miss it.
Plain-English guide to Medicare, Medigap, Advantage, and Part D — 2026 rates included.
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Your Medigap Open Enrollment Period is a one-time, six-month window that begins the first month you are both 65 or older (learn more about allianz index advantage annuity review: independent analysis (2026)) and enrolled in Medicare Part B. During those six months, any insurer selling Medicare Supplement policies in your state must sell you any plan it offers at its standard rate — no health questions, no medical underwriting (learn more about medicare advantage vs medicare supplement) (learn more about estate tax guide: minimize taxes and protect your legacy) (learn more about 15 questions to ask before buying an annuity (that your agent may not volunteer)), no denial for a pre-existing condition. It is the single strongest enrollment protection in Medicare, and unlike the fall Annual Enrollment Period you hear advertised every October, it does not come back around. This guide explains when your window opens, what happens if you miss it, (learn more about tax-free retirement income: complete guide) (learn more about retirement income strategies for 2025) and the four narrower doors that remain open afterward.
These two windows share a name and almost nothing else. The Medicare Annual Enrollment Period (October 15 – December 7) lets you change Medicare Advantage and Part D drug plans every single year. Your Medigap Open Enrollment Period happens once in your lifetime, is tied to your own Part B start date rather than the calendar, and is the only time federal law guarantees you a Medicare Supplement policy regardless of your health.
A great many people learn this distinction the hard way. They take Original Medicare at 65, skip the supplement because they feel healthy, and return three years later after a diagnosis — only to find the same policy now requires a health questionnaire they cannot pass.
We ranked the routes into a Medigap policy by how much protection each one actually gives you:
| Criteria | Weight | Why It Matters |
|---|---|---|
| Underwriting protection | High | Whether the insurer may ask health questions or decline you |
| Plan selection | High | Whether you can choose any plan or only a short federally-specified list |
| Who qualifies | High | Broad federal right vs. narrow state or circumstantial eligibility |
| Timing control | Medium | Whether you choose when to use it or an outside event triggers it |
| Pricing | Medium | Whether you pay the standard rate or a health-rated premium |
Sources: Medicare.gov, the Centers for Medicare & Medicaid Services, the CMS Medigap guidance bulletin, and Medicare Interactive.
Best for: Everyone turning 65 and enrolling in Part B
Length: 6 months
Starts: The first day of the month you are 65 and enrolled in Part B
Your Medigap Open Enrollment Period runs for six calendar months beginning the first day of the month in which you are both 65 or older and enrolled in Medicare Part B. If your Part B coverage starts March 1, your window closes August 31. Inside it, insurers cannot ask health questions, cannot charge you more because of a condition, and cannot turn you down for any Medigap plan they sell in your state.
Anyone who wants a Medicare Supplement policy at any point in retirement should buy it here, even if their budget feels tight at 65. If you expect to stay on an employer group plan past 65 and delay Part B, your window simply starts later — it is not lost. If you are certain you want a Medicare Advantage plan instead, understand that switching back to Original Medicare later will not reopen this window. Our Medicare plans comparison guide walks through that fork in detail.
Best for: People who lose coverage through no fault of their own
Length: Typically 63 days from the qualifying event
Plan selection: Limited federally-specified plans
Federal guaranteed-issue rights (sometimes called Medigap protections) reopen underwriting-free access when specific events occur: your Medicare Advantage plan leaves your service area, your employer retiree coverage ends, your Medigap insurer goes insolvent, or you exercise a "trial right" by dropping a first-time Medicare Advantage plan within 12 months. You generally have 63 days from the loss of coverage to apply.
Retirees losing group coverage and anyone whose Medicare Advantage plan is exiting their county. Plan exits have hit a number of markets recently, and the resulting guaranteed-issue right is the most commonly missed protection in Medicare. This is not a substitute for enrolling during your own window — the plan menu is narrower and you have no control over the timing.
Best for: Existing Medigap holders who want to shop for a lower premium
Length: Usually 30–60 days around your birthday or policy anniversary
Availability: A minority of states, and the list has grown
Roughly a dozen and a half states now let current Medigap policyholders switch carriers each year without underwriting, usually within a short window around their birthday. California, for instance, gives you 60 days from the first day of your birth month to move to a plan with equal or lesser benefits. Kentucky, Utah, Virginia, Indiana, Wyoming, and Delaware have all added versions of the rule recently.
Anyone who already owns a supplement in a birthday-rule state and has watched their premium climb. Rules change by legislative session, so confirm current terms with your State Insurance Department rather than relying on any article, including this one.
Best for: Residents of Connecticut, New York, Massachusetts, and Maine
Length: Year-round or an annual window
Plan selection: Broad
Connecticut and New York require Medigap insurers to accept applicants year-round regardless of health. Massachusetts and Maine provide annual guaranteed-issue windows. If you live in one of these states, missing your six-month window is far less costly than it is elsewhere — though premiums in continuous-issue states tend to run higher, because carriers price for the fact that anyone can join at any time.
Residents of those states who are past 65 and uninsured by a supplement. Everyone else should treat this as a reminder that protections are geographic, not universal.
Best for: Healthy applicants past their window with no other protection
Length: Anytime
Plan selection: Whatever the carrier approves you for
Outside every protection above, you may still apply for a Medigap policy at any time. The insurer will ask health questions, may review your prescription history, and may decline you or quote a higher rate. Approval is common for applicants in good health and uncommon for applicants with recent cardiac events, cancer treatment, insulin-dependent diabetes, or oxygen use.
Applicants in good health who missed their window and live outside a protected state. It is worth applying before assuming you cannot qualify — but it is not a plan, and it is why the six-month window matters so much.
| Enrollment Path | Underwriting? | Plan Choice | Who Qualifies | Typical Length |
|---|---|---|---|---|
| Medigap Open Enrollment | Never | Any plan sold in your state | Age 65+ and newly on Part B | 6 months, once |
| Federal guaranteed issue | Never | Limited federal list | Loss of other coverage; trial rights | ~63 days per event |
| State birthday/anniversary rule | Never | Usually equal or lesser benefits | Existing Medigap holders in ~18 states | 30–60 days yearly |
| Continuous/annual issue states | Never | Broad | CT, NY, MA, ME residents | Year-round or annual |
| Medical underwriting | Yes | Whatever is approved | Anyone may apply | Anytime |
A supplement pays after Original Medicare pays, so the 2026 cost-sharing figures are what your policy is actually absorbing:
Plan G covers everything except that Part B deductible. Plan N covers the same core benefits with small copays at office and emergency visits and no coverage of Part B excess charges. Our side-by-side of Plan G versus Plan N compares the math, and the Medicare cost calculator guide helps you total your own year.
This guide draws on Medicare.gov's Medigap enrollment guidance, the CMS bulletin on the timing of the six-month Medigap Open Enrollment Period, the CMS 2026 Parts A and B premiums and deductibles fact sheet released November 14, 2025, and Medicare Interactive's guaranteed-issue reference. We cross-checked state birthday-rule counts against multiple 2026 state-by-state trackers and excluded any state protection we could not corroborate, because these rules change by legislative session. Figures reflect 2026 amounts. Last updated: September 23, 2026. We review this guide at least twice a year and after each CMS rate announcement.
It starts on the first day of the month in which you are both 65 or older and enrolled in Medicare Part B, and it runs for six calendar months. If Part B starts March 1, your window closes August 31.
No. Federal law provides it once. If you drop a Medigap policy and later want one back, you are subject to underwriting unless a guaranteed-issue right or a state rule applies.
Your window has not been lost — it simply has not started. It begins when your Part B coverage begins, which for most people working past 65 is when the employer coverage ends.
Federal law ties the guaranteed window to age 65, so many people on Medicare through disability do not get a full one before then. Some states require carriers to sell to under-65 beneficiaries. You do get a Medigap Open Enrollment Period when you turn 65.
It cannot refuse to sell you the policy. If you had less than six months of prior creditable coverage, it may delay coverage of a pre-existing condition for up to six months.
No. The October 15 – December 7 Annual Enrollment Period is for Medicare Advantage and Part D and repeats yearly. The Medigap window is personal to you and happens once.
You can apply, but generally with underwriting — unless you use a trial right within the first 12 months on your first Medicare Advantage plan, which restores guaranteed issue.
Premiums vary by plan letter, ZIP code, age, tobacco use, and the carrier's rating method. A supplement premium is on top of your $202.90 standard Part B premium in 2026. Compare the leading Medigap plans for 2026 before assuming a price.
No. Medigap sold today does not include drug coverage. You need a separate Part D plan, and going without one can trigger a late enrollment penalty.
Check three things in order: whether a guaranteed-issue event applies, whether your state has a birthday or anniversary rule, and whether you can pass underwriting. Your State Health Insurance Assistance Program offers free, unbiased help with all three. Medicare Supplement Insurance Explained covers the basics if you are starting from scratch.
This content is for educational purposes only and does not constitute insurance, financial, or legal advice. SeniorSimple is not connected with or endorsed by the United States government or the federal Medicare program. Plan availability, premiums, standardized benefits, and state enrollment protections vary by state and change frequently — the state rules described here were accurate as of publication and are set by state legislatures and insurance departments, not by us. Verify your own dates and options with Medicare.gov, your State Insurance Department, or your free State Health Insurance Assistance Program before making a decision. Last updated: September 23, 2026.
About this guide: Written and reviewed by the SeniorSimple editorial team, which has covered Medicare enrollment rules, supplement pricing, and retirement health coverage since 2019. We do not accept payment from insurance carriers for placement or ranking.
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