The short answer
Your Medigap Open Enrollment Period is a 6 month window that starts the first month you have Medicare Part B and you are 65 or older. Inside it, an insurance company cannot refuse you a policy, cannot use medical underwriting, and cannot charge you more because of pre-existing health problems.
Say you feel well at 65, so you wait a year before shopping for Medigap. The same policy is still for sale. You are simply no longer guaranteed it, and the company may now ask about your health.
When is my Medigap open enrollment period?
Your Medigap Open Enrollment Period is the 6 month window that starts the first month you have Medicare Part B and you are 65 or older. Federal law sets it. A policy bought inside it generally begins the first of the month after you apply, unless you ask for a different effective date.
Two conditions have to be true at the same time for the clock to start. You have Part B, and you are 65 or older. Someone who has Part B at 63 does not start the window until the month they turn 65.
Inside the window, three protections apply at once. You can enroll in any Medigap policy the company offers. You generally get better prices and more choices. And your coverage starts right away, with no waiting period the company can impose except for coverage related to a pre-existing condition.
You also need Original Medicare to buy at all. Generally that means Part A and Part B are both in place before a Medigap policy can be bought.
Does Medigap open enrollment repeat every year?
The Medigap Open Enrollment Period is a one time enrollment period. It does not repeat every year, unlike the Medicare Open Enrollment Period. Call it the One Time Door: it is the only route into Medigap that depends on a date rather than on a situation.
The One Time Door is our naming for what three published rules do together. The window is the only period in which no medical question may be asked at all. It happens once. And every other way in depends on something happening to you, such as losing other coverage, rather than on a date you can plan around.
That is the practical difference worth carrying. Medicare Open Enrollment runs October 15 to December 7 and comes round again. A Medigap Open Enrollment Period you miss does not come back at all.
The confusion is common enough that Medicare.gov says it twice, on two separate pages, in almost the same words.
What are guaranteed issue rights?
Guaranteed issue rights, also called Medigap protections, are situations where an insurance company cannot deny you a Medigap policy. With one, a company must sell you a policy, must cover all your pre-existing health conditions, and cannot charge you more because of past or present health problems.
In most cases you have one when your other health coverage changes in some way, such as losing that coverage. Medicare.gov also names a trial right: you may be able to try a Medicare Advantage plan and still buy a Medigap policy if you change your mind.
Two very different doors lead to a Medigap policy, and only one of them is open to everyone.
| Open enrollment | Guaranteed issue | |
|---|---|---|
| When it happens | Once, when you first have Part B at 65 | Only after certain events |
| Health questions | Not allowed | Not allowed |
| What triggers it | Turning 65 with Part B | Losing other coverage, in defined situations |
Outside both of those doors, a company may ask about your health and may decline you or charge more.
There is a deadline attached, and it is easy to miss. Apply no more than 63 days after your coverage ends. Keep copies of letters, notices, emails or claim denials as proof the coverage was terminated, because they may need to go with the application to prove the right.
Notice what a guaranteed issue right is not. It is not a date, and it is not something you can schedule. It is a description of a situation, and the situation has to happen to you before the right exists at all.
That is the structural reason the open enrollment window matters so much. The window is the one route in that arrives on a schedule you can see in advance, which makes it the only one you can plan around.
What happens if I apply late?
Applying after your Medigap Open Enrollment Period ends changes three things. You may have to pay more for a policy, fewer policy options may be available, and the insurance company is allowed to deny you a policy if you do not meet its medical underwriting requirements.
Medicare.gov states the harder version of that on the basics page: after the period, you may not be able to buy a Medigap policy at all, or it may cost more.
The word allowed matters in the middle item. Outside the window, and without a guaranteed issue right, underwriting moves from banned to permitted. Whether a particular company uses it, and how strictly, is the company's decision.
Price can move too. Whether a company uses medical underwriting, or charges a different premium, when you have no guaranteed issue right and are outside your open enrollment period is one of the listed things that affects what a Medigap policy costs.
Can I be denied for health reasons?
Whether you can be denied a Medigap policy for health reasons depends on when you apply. Inside your Medigap Open Enrollment Period an insurance company cannot refuse to sell you any policy it offers, cannot use medical underwriting, and cannot deny you for pre-existing health problems.
Outside that window, and without a guaranteed issue right, the company is allowed to deny you if you do not meet its medical underwriting requirements.
There is one narrow exception inside the window, and it is about timing rather than acceptance. A company cannot make you wait for coverage to start, except for coverage related to a pre-existing condition.
Under 65, the picture is different again. If you have Medicare because of a disability or End-Stage Renal Disease, you might not be able to buy a Medigap policy until you turn 65, because federal law generally does not require companies to sell Medigap to people under 65.
Do state rules change Medigap enrollment?
State law can add rights beyond the federal ones, and Medicare.gov's instruction is to check with your State Insurance Department. Two state facts are stated nationally: Medigap is standardized differently in Massachusetts, Minnesota and Wisconsin, and some states sell Medigap to people under 65.
Medicare.gov does not publish a list of which states do the second one, and no list is invented here. Its answer for both the under 65 question and the buying outside your window question is the same: check with your State Insurance Department about what rights you might have under state law.
That is worth doing even when the federal answer looks final. The federal rules are a floor, and a state can build above them.
One state-level product is worth knowing about while you are asking. In some states you can buy a Medicare SELECT policy, a type of Medigap that may require using particular hospitals and, in some cases, particular doctors to get full benefits. Its premium may be lower for that reason, and buying one carries a right to change your mind within 12 months and switch to a standard Medigap policy.
What this means for you
The Medigap window is short, it is personal to you rather than a calendar date everyone shares, and it happens once. Inside it, health is not a question anyone may ask. Nothing else in Medigap gives you all three of those at the same time.
After it closes, buying a policy becomes conditional. Either a guaranteed issue situation applies to you, or the company may ask about your health and may say no.
If a guaranteed issue situation does apply, the 63 day clock and the paperwork are the two things that decide whether the right is usable in practice.
For what the lettered plans actually cover, read the Plan G and Plan N article in this cluster. For changing a policy you already hold, read the switching article beside it.
FAQ
What starts the 6 month clock, Part B or turning 65?
Both, and the later of the two is what matters. Medicare.gov states that the Medigap Open Enrollment Period starts the first month you have Medicare Part B and you are 65 or older, so the two conditions have to be true at the same time.
For most people the two arrive together and the question never comes up. For someone who took Part B earlier, for example while under 65 with Medicare through a disability, the window does not open on the Part B date.
It opens in the month they turn 65, provided Part B is in place. That distinction is the whole answer for a large group of people who assume their window has already been used or already expired.
Can I buy a Medigap policy outside my open enrollment period?
Sometimes. Medicare.gov's phrasing is that there are certain situations where you may be able to, and that the situations where an insurance company cannot deny you are called guaranteed issue rights or Medigap protections.
In most cases you have one when your other health coverage changes in some way, such as losing that coverage, and there is also a trial right for someone who tried a Medicare Advantage plan and changed their mind.
Outside those situations, a company is allowed to apply medical underwriting and may decline you. Medicare.gov also advises checking with your State Insurance Department, because you may have additional rights under state law that the federal rules do not provide.
What does a guaranteed issue right actually force a company to do?
Three specific things, all of them stated on Medicare.gov. The company must sell you a Medigap policy. It must cover all your pre-existing health conditions. And it cannot charge you more for the policy because of past or present health problems.
That is a stronger protection than it may first appear, because it removes both the ability to refuse and the ability to price around the refusal. What it does not do is remove the deadline.
The application has to be made no more than 63 days after your coverage ends, and Medicare.gov advises keeping copies of letters, notices, emails or claim denials as proof the coverage was terminated, because that proof may need to be submitted with the application.
Does my Medigap coverage start right away?
Inside your Medigap Open Enrollment Period, yes, with one exception. Medicare.gov states that an insurance company cannot make you wait for coverage to start, except for coverage related to a pre-existing condition. Separately, it states that a Medigap policy will generally begin the first of the month after you apply, unless you ask for a different effective date.
So the normal pattern is a start date at the beginning of the following month, and the one thing that can be delayed beyond that is coverage tied to a condition you already have.
If you are switching from another Medigap policy rather than buying your first one, a different set of pre-existing condition rules applies, and those are covered in the switching article in this cluster.
I am under 65 and on Medicare. Can I buy Medigap?
Possibly, but federal law does not guarantee it. Medicare.gov states that if you are under 65 and have Medicare because of a disability or End-Stage Renal Disease, you might not be able to buy a Medigap policy until you turn 65.
The reason is that federal law generally does not require insurance companies to sell Medigap policies to people under 65. It also states that in some states insurance companies do offer them. It does not publish which states, and no list is invented here.
The route Medicare.gov gives is to check with your State Insurance Department about what rights you might have under state law. Turning 65 while already on Medicare also opens a Medigap Open Enrollment Period at that point, provided Part B is in place.
