The six months that decide whether you can ever buy Medigap
One window, once, and it does not reopen. Inside it no insurer can ask about your health. Outside it, in most states, they can ask anything and say no.
Most Medicare deadlines are annoying. You miss one, you pay a penalty, you carry on. This one is different in kind: miss it and a product you wanted may simply stop being available to you, for the rest of your life, because of your medical history.
It is called the Medigap open enrollment period. It lasts six months, it happens once, and almost nobody is told what it costs to let it pass.
| How long | Six months. One time. It does not repeat and it cannot be reopened. |
|---|---|
| When it starts | The first month you are both 65 or older and enrolled in Part B — not your birthday. Delaying Part B for employer coverage delays this too. |
| What it guarantees | Any Medigap policy sold in your state, at the standard rate, with no health questions and no refusal. |
| What closes with it | In most states, insurers may then ask your full medical history, charge you more for it, or decline you outright. |
| Where the rules are better | A few states — New York, Connecticut, Massachusetts and Maine among them — require guaranteed issue beyond this window. The rules differ between them, so check your own. |
| If you move | Those state protections do not travel with you. They belong to the state you live in, not to you. |
What underwriting actually means here
Inside the window, the application asks your name, your address and your Medicare number. Outside it, in most of the country, the application asks about your health — and the answers decide the outcome.
This is not a formality that ends with a higher price. Insurers can and do decline applications outright. The conditions that cause trouble are the ordinary ones people accumulate in their sixties and seventies, not exotic ones. Someone perfectly healthy at 65 who buys nothing, and returns at 70 after a cardiac event or a cancer diagnosis, is applying in a different world from the one they left.
Also on The Second Half Guide Most states will let you take college classes free after 60 Most states have some provision letting older residents take public-college courses free or cheaply. It is one of the best-kept and least-claimed benefits in the country — and the rules vary more than anyone tells you. Read it →Why people miss it
Almost always for a reason that felt sensible at the time.
- They chose Medicare Advantage at 65, which is a perfectly reasonable choice — but the Medigap window ran out in the background while they were in it.
- They were still working with employer coverage, delayed Part B, and did not realize the Medigap clock had not started rather than being paused indefinitely.
- They looked at the premium at 65, decided they were healthy and did not need it, and planned to revisit the question later. Later is the problem.
- Nobody ever mentioned it. It is not on the enrollment paperwork and it is not what the advertising is about.
The exceptions worth knowing
The window is not the only route to guaranteed issue, and if you are outside it the exceptions are where to look first. Federal rules create guaranteed-issue rights in specific circumstances — among them losing employer or union coverage that was paying alongside Medicare, and a Medicare Advantage plan leaving your area or ending its contract.
There is also a trial right: if you joined a Medicare Advantage plan when you first became eligible at 65, you generally have twelve months to switch back to Original Medicare and buy a Medigap policy with guaranteed issue. Twelve months, from the start of that plan. It is a genuine safety net and it is easy to spend without noticing.
These rights are narrower than the open enrollment window, they come with their own timing rules, and they are worth confirming with your state's own program rather than an insurer's salesperson.
The decision at 65 is not only which coverage you want now. It is whether you keep the option of changing your mind later.
What to do about it
If you are approaching 65, find out exactly when your six months start — it hangs on your Part B enrollment date, not your birthday — and write the end date down. Decide inside it, not after.
If you are still working past 65 on employer coverage, the window opens when you take Part B. That is usually when you retire, and it is the moment to have this decision already made rather than to start thinking about it.
If the window has closed, it is still worth applying rather than assuming the answer. Underwriting standards vary between insurers, and a decline from one is not a decline from all. Check whether your state has broader rules, and check whether any guaranteed-issue right applies to your situation.
Free help exists and does not sell anything: every state has a SHIP, a State Health Insurance Assistance Program, with counselors who earn no commission whichever way you go. Their number is on our page of numbers worth keeping by the phone.
This is general information, not personal advice. We report the rules, the numbers and the deadlines as clearly as we can. We don't know your income, your state, your health or your family — and all four can change the answer. Treat this as a good place to find the right questions, not a substitute for someone looking at your actual situation.
Where these facts come from
Checked on 10 August 2026 against the sources listed below. Dollar limits and program rules change — if you're reading this well after that date, verify the numbers at the links below.
- Medicare — When can I buy Medigap? — https://www.medicare.gov/health-drug-plans/medigap/ready-to-buy
- Medicare Interactive — Medigap enrollment periods and guaranteed issue — https://www.medicareinteractive.org/understanding-medicare/health-coverage-options/supplemental-insurance-for-original-medicare-medigaps/medigap-purchasing-details-enrollment-periods-guaranteed-issue-and-more
- NCOA — Medigap open enrollment — https://www.ncoa.org/article/medigap-open-enrollment-period/
- SHIP — free local Medicare counseling — https://www.shiphelp.org/
Edward Silva
Edward spent more than forty years as a computer professional — long enough to pick up one useful occupational habit: when somebody hands you a summary, go and read the actual documentation. He started The Second Half Guide after noticing that most writing aimed at people his age was either talking down to him or quietly selling him something, and that the plain facts — the dates, the thresholds, the dollar figures — were somehow the hardest part to find.
He's married, with two grown sons, both married themselves. He is not a financial adviser, an attorney or an insurance agent, and this site doesn't tell you what to do with your money. It tells you what the rules actually say, and links to where he checked.