Your Medigap open enrollment period is a one-time, six-month window that starts the first day of the month you are both 65 or older and enrolled in Medicare Part B. During those six months, any insurer selling Medigap in your state must sell you the policy you choose, at the price it charges for your age, whatever your health history. It does not come back every fall, and missing it can be expensive. Here is exactly how it works, what happens if you miss it, and what Florida adds on top of federal law.
TL;DR
- Medigap open enrollment lasts 6 months and starts the first month you have Part B and are 65 or older. It happens once.
- Inside the window, insurers cannot deny you, charge more for health conditions, or make you answer medical questions.
- Outside it, you may face medical underwriting, unless a specific guaranteed-issue right (such as the Medicare Advantage trial right) applies.
- Florida requires insurers to offer Medigap to people under 65 on Medicare due to disability or ESRD, and a new window opens when they turn 65.
- Do not cancel an old policy until the new one is in force and you have decided to keep it.
Table of Contents
- When your Medigap open enrollment period begins and ends
- What insurers can and cannot do during the window
- What happens if you miss it
- The Medicare Advantage trial right
- Florida rules that change the picture
- How to use your window well
- What we see in Southwest Florida
- Talk it through with a local agent
- FAQ
- Sources
When your Medigap open enrollment period begins and ends
The rule is simple, and the timing is where people slip. Medicare says the six-month period starts the first month you have Part B and you are 65 or older. Two conditions must both be true. If you turn 65 in June but your Part B starts in August because you kept working, your window starts in August, not June.
For most people who sign up on time, the window lines up with the first six months of Part B. Here is how that plays out:
| Your situation | When your Medigap window starts |
|---|---|
| Turn 65 and start Part B the same month | That month (the first day of it) |
| Turn 65, delay Part B because of employer coverage | The month Part B starts |
| Already on Part B at 64 (for example, due to disability) | The month you turn 65 |
A detail that catches Floridians: if your birthday falls on the first day of the month, Medicare treats you as turning 65 the month before. According to the Florida Department of Financial Services, your Part B coverage and your Medigap open enrollment then begin on the first day of the previous month. If you were born on the 1st, count backward one month before you plan.
It is not the same as the fall Medicare enrollment
Many readers confuse the two. The fall Medicare open enrollment is an annual period for changing Medicare Advantage and Part D plans. Medigap open enrollment is personal to you and happens once. You can apply for a Medigap policy in the fall, but Medicare’s switching guidance says that in most cases you have no federal right to switch policies unless you are inside your six-month window or have a specific guaranteed-issue right. Without one, the insurer can look at your health.
What insurers can and cannot do during the window
Inside your six months, Medicare states that insurers cannot:
- Refuse to sell you any Medigap policy they offer.
- Charge you more because of a pre-existing condition.
- Use medical underwriting to accept or reject your application.
That last point is the real value. You choose the plan letter that fits your life, such as Plan G or Plan N, and the insurer cannot ask about your heart, your diabetes or last year’s surgery as a condition of selling it. In Florida, Section 627.6741 of the Florida Statutes requires companies to provide an open enrollment period and not discriminate in pricing based on the enrollee’s medical condition.
One caution from the same Medicare page: a Medigap policy can still have a waiting period for pre-existing conditions in some cases, so ask each insurer about it in writing before you apply, and ask what credit you get for prior coverage.
What happens if you miss it
After the six months, the protection is gone. Medicare warns that after this period you may not be able to buy a Medigap policy, or it may cost more. Federal law does not guarantee the right to buy outside open enrollment or a guaranteed-issue window, so an insurer can:
- Ask you health questions (medical underwriting).
- Decline your application.
- Charge a higher premium based on your current or past conditions.
In practice, a healthy 67-year-old may sail through and a person with a recent cancer diagnosis may be turned down. You will not know which until you apply, and a decline can follow you into the next application. That is why the first six months matter so much, even if you feel well today and think Original Medicare alone is enough.
Because Medigap exists to cover your share of Original Medicare costs, it helps to know what Part B pays in the first place. If you use services like physical therapy or spinal care, this explainer on what Part B actually pays for chiropractic care shows how the 20% coinsurance on covered services shows up in real life, and why that share is what a Medigap plan is designed to absorb.
The Medicare Advantage trial right
The other query we hear most is about the “trial right.” It is a second protected window, and it matters if you try Medicare Advantage and change your mind.
Per Medicare’s Advantage plan guide, if you join a Medicare Advantage Plan for the first time when you are first eligible at 65 and decide within 12 months that you want Original Medicare back, you have a federal right to buy a Medigap policy. During that period, insurers must issue it on a guaranteed basis: no denial, no higher price because of health.
A few practical points:
- It applies to a first-time Advantage enrollment at 65. Someone who switched into Advantage at 70 after years on Original Medicare generally does not have this right under federal law.
- Dropping the Advantage plan sends you back to Original Medicare. Medicare’s page on special enrollment periods says you will automatically switch back, and that you get special rights to buy a Medigap policy for a limited time.
- Line up the dates. Apply for the Medigap policy so it starts when your Advantage coverage ends. Do not leave a gap in between.
The trial right is also why some people on Original Medicare feel comfortable trying an Advantage plan first. It is a safety net, not a guarantee for every future change, and it expires. If you are weighing the two paths, our guide to the core differences between Original Medicare and Medicare Advantage lays them side by side.
Medigap and Advantage do not mix
The State Health Insurance Assistance Program (SHIP) explains that Medigap works with Original Medicare only. If you are in a Medicare Advantage Plan, it is illegal for someone to knowingly sell you a Medigap policy. And if you choose Advantage, you should generally cancel your Medigap, because it will not cover Advantage copayments or deductibles. Before you cancel anything, though, make sure you understand whether you could get it back. After the trial period, you may not.
Florida rules that change the picture
Federal law sets the floor. States can add to it, and Florida does in a few ways that matter for Fort Myers, Cape Coral and Naples residents.
Under 65 with a disability or ESRD
Federal law gives a guaranteed Medigap window only to people 65 and older. KFF notes that this right does not extend to beneficiaries under 65 who qualify for Medicare through disability. Many states fill that gap, and Florida is one of them. The Florida Department of Financial Services says Florida requires all Medigap insurers to offer policies to people under 65 who qualify because of a disability or End-Stage Renal Disease, with a dedicated six-month window regardless of health. Premiums for those plans are typically higher than for people who qualify by age.
Here is the step many people miss. When you turn 65, you receive a new open enrollment period, but you have to apply for a new policy yourself to move to the lower age-eligible rates. Nobody does it for you. If you are 64 and on Medicare through disability, put your 65th birthday month on the calendar now.
Issue-age rating
Florida uses issue-age rating. The state explains that your premium is set by your age when you buy the policy and does not rise just because you get older. Insurers can still raise rates for other reasons, such as inflation or area-wide changes, and if you switch insurers later, you are rated on your older age at that point. This is one reason buying at 65 and staying put can make sense, and why switching later deserves a careful look at the numbers, not just this year’s price.
How to use your window well
Six months is plenty of time, but only if you start early. A workable plan:
- Find your exact start date. Check your Part B effective date on your Medicare card or your Social Security account, and remember the first-of-the-month birthday rule.
- Decide whether Medigap or Advantage fits you. Think about how often you see specialists, whether you split the year between Florida and another state, and how much cost uncertainty you can tolerate.
- Compare the same plan letter across carriers. Within a given letter, Medigap benefits are standardized, so the differences come down to price, rating method, and the company’s track record on rate increases.
- Ask about waiting periods and discounts before you apply.
- Apply early in the window, not in the last week. A delay leaves little room to fix a mistake.
- Use your free-look period. Medicare advises that if you buy a policy and later find a better one, you have a 30-day free look after the new policy starts. Do not cancel your first policy until you are sure you are keeping the second, so you never fall into a coverage gap.
Snowbirds
Medigap is designed to work nationwide with Original Medicare, which is why many part-year residents prefer it to a network-based plan. Still, your state of residence affects which protections apply to you. Check with your State Insurance Department about state-specific rules beyond federal law, particularly if you are changing your permanent address.
What we see in Southwest Florida
We are an independent agency in Fort Myers, and the same pattern repeats. Someone retires, keeps working part-time or stays on a spouse’s employer plan, assumes Medicare will sort itself out, and then realizes the six-month window began months ago. The reverse happens too: a newly eligible person feels pressure to buy the first plan a mailer offers, simply because they think the clock is running out.
Our view is that the window exists to protect you from both mistakes. Because it guarantees acceptance, you do not need to rush on day one. You also should not coast. We encourage people to start looking about 60 to 90 days before their Part B start date, learn what Medigap covers and what it does not, and then compare carriers on the same plan letter. We work with multiple carriers, so the comparison is not built around one company’s product. The goal is a plan you understand, not just one you signed.
We also pay special attention to gaps people rarely ask about until they need them, such as emergency ground and air transport, which can arrive as a surprise bill. If you want to understand how that fits with Medigap, our article on emergency transport coverage options for seniors is a good place to start.
— Alston
Talk it through with a local agent
If your window is open, opening soon, or you are not sure whether it has already passed, we offer free, no-obligation consultations. We will confirm your dates, explain the plan options and compare carriers for you. You can see our Medicare Supplement options in Southwest Florida or read why many people choose Medigap at enrollment. If Part B timing is the worry, our piece on avoiding Medicare late enrollment penalties covers the related deadlines.
FAQ
When is Medigap open enrollment?
It is a six-month period that begins on the first day of the month you are 65 or older and enrolled in Medicare Part B. It is tied to you, not to the calendar, so it differs for every person. It happens once and does not repeat each year.
Can you be denied Medigap during open enrollment?
No. During your window, insurers must sell you any Medigap policy they offer, cannot charge more for health conditions, and cannot use medical underwriting. Outside the window, and without a guaranteed-issue right, a denial is legally possible.
What is the Medigap trial right?
If you join a Medicare Advantage Plan when you first become eligible at 65 and leave it within 12 months, you can buy a Medigap policy on a guaranteed-issue basis. The insurer cannot deny you or raise your price over health. It applies to a first-time Advantage enrollment, so check your dates before you drop a plan.
Can I buy Medigap under 65 in Florida?
Yes, if you have Medicare because of a disability or ESRD. Florida requires Medigap insurers to offer policies to you with a six-month window, though premiums are typically higher than for age-eligible buyers. You get another window at 65 and must apply to move to the lower rates.
Sources
- Get ready to buy | Medicare
- When can I buy a Medigap policy? | Medicare
- Can I change my Medigap policy? | Medicare
- Understanding Medicare Advantage Plans | Medicare
- Special Enrollment Periods | Medicare
- Medicare Supplement Insurance Overview | Florida Department of Financial Services
- Key Facts About Medigap Enrollment and Premiums | KFF
- Medigaps | State Health Insurance Assistance Programs
- Medicare chiropractic coverage: what Part B pays for
Recommended
- Top Reasons to Choose Medigap at Enrollment
- How to Avoid Costly Medicare Late Enrollment Penalties in 2026
- Medigap Coverage Explained for Medicare Beneficiaries
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