There is one window in Medicare where the insurance company does not get a vote. It lasts six months, it opens once, and a surprising number of people spend it deciding whether to redo the kitchen.
Your Medigap open enrollment period begins the month your Part B takes effect, provided you are 65 or older. For those six months, any Medicare Supplement carrier selling in your state must sell you any plan it offers, at its best available rate for your age, regardless of your health history (Medicare.gov).
Not sure when yours runs? The enrollment window checker will give you the exact dates from your date of birth.
What exactly is Medigap open enrollment?
It is a federal guarantee, and it is narrower than most people assume.
Two conditions have to be true at the same time: you are 65 or older, and your Part B is in effect. The clock starts on the first day of the month those two things overlap, and it runs for six months. It is not tied to your birthday, not tied to the fall Annual Enrollment Period, and not repeatable.
Inside the window, a carrier cannot:
- ask health questions that affect whether it accepts you,
- charge you more because of a condition you already have,
- or refuse to sell you a plan it offers to anyone else your age.
There is one thing it can still do: apply a pre-existing condition waiting period of up to six months for a condition treated or diagnosed in the six months before coverage started — and even that is generally waived if you had prior creditable coverage. It is a much smaller catch than the one waiting outside the window.
What changes when it closes
Everything, quietly. After those six months, in most states a Medigap carrier may:
- ask about your health history and your prescriptions,
- charge you more than the standard rate,
- or decline your application outright.
| Inside your 6-month window | After it closes | |
|---|---|---|
| Health questions | Not asked | Asked, and they decide the outcome |
| Can you be declined? | No | Yes, in most states |
| Rate you are offered | Best available for your age | May be loaded, or no offer at all |
| Plans available to you | Every plan the carrier sells | Whatever it will underwrite you for |
| How often this comes around | Once | — |
Nothing announces this. Your coverage does not change on the last day of the window. What changes is your optionality — and you only find out how much you lost when you try to use it, often years later when a plan gets expensive or a network drops your hospital.
The choice this quietly makes for you
Here is the asymmetry that matters at 65, and the reason this is worth thinking about carefully rather than quickly:
- If you take a Medicare Supplement now, you can switch to Medicare Advantage later. Advantage plans accept you regardless of health during any valid enrollment period.
- If you take Medicare Advantage now, switching to a Supplement later may require passing underwriting.
The doors are not equally easy to walk back through.
That does not make Advantage the wrong choice. For plenty of people, in plenty of counties, it is genuinely the better plan, and the premium difference is real money every month for the rest of your life. Hillsborough County alone has 133 Medicare Advantage and Part D plan options for 2026 (source: CMS CY2026 Landscape), and some of them are strong.
It makes it a choice worth understanding as a one-way door rather than a preference you can revisit at leisure. The honest framing is not “which is better” but “which risk would you rather hold” — the monthly premium of a Supplement, or the possibility that your health closes the route back to one.
Why this matters more in Florida
A small number of states add their own switching rights on top of the federal rules. Some have a birthday rule letting you change Medigap plans each year around your birthday without underwriting; others run an annual guaranteed-issue window.
Florida is not one of them. Here, the federal six-month window is essentially the whole protection, which means the decision you make at 65 carries more weight in Tampa than it would in a birthday-rule state.
One more Florida detail with money attached: Florida permits Part B excess charges, the amount a non-participating provider may bill above the Medicare-approved rate. Plan G covers those charges and Plan N does not. In a state that allows them, that difference is not theoretical.
State rules change. Confirm the current position with the Florida Department of Financial Services rather than taking any agency’s word for it, including ours.
Guaranteed issue: the narrow escape hatches
Certain events reopen your right to buy specific Medigap plans without underwriting (Medicare.gov). The common triggers include:
- your employer or union coverage ending,
- your Medicare Advantage plan leaving your service area, or you moving out of its service area,
- your Medigap carrier going insolvent or the coverage ending through no fault of yours,
- a carrier or agent misleading you,
- the trial right: if you joined Medicare Advantage when you first became eligible at 65 and change your mind within twelve months, or if you dropped a Medigap policy to try Advantage for the first time and switch back within twelve months.
That last one is the most commonly missed, and it is genuinely useful — but note how tightly it is drawn. It is a first-time trial, inside twelve months. It is not a general right to reconsider at 70.
Two practical consequences:
- The trigger date is the whole game. Keep the letter. Note the date. The clock — usually 63 days — runs from the event, not from when you got around to reading the mail.
- Do not plan around a guaranteed-issue right you do not yet have. They are a backstop, not a strategy.
What if the window has already closed?
Then you have fewer options, not none, and it is worth being systematic rather than discouraged.
Apply anyway, and apply well. Underwriting is not a single national standard. Carriers differ substantially in how they treat specific conditions, medications and time since a procedure. A decline from one company is not a decline from the category, and the questions on the application are not identical between them.
Check whether a guaranteed-issue right is live. Run through the trigger list above against the last 63 days before assuming it is closed.
Reconsider the Advantage plan you have, properly. If underwriting is not available to you, the real decision moves to choosing well among the plans that must accept you — network, drug formulary, maximum out-of-pocket, and the supplemental benefits that vary plan to plan. That is a genuine optimisation, not a consolation prize.
Watch the timing of any future move. If your health improves or a procedure moves further into the past, the answer can change. Underwriting reads the last two to five years, depending on the question.
What underwriting actually asks
“They check your health” is vague enough to be frightening without being useful. In practice a Medigap application outside your window asks a fairly predictable set of things:
- Height and weight, against a build chart.
- Current medications, which is usually the most revealing question on the form — a drug list tells an underwriter the diagnosis even when the diagnosis question is answered narrowly.
- Knockout conditions: a defined list where an affirmative answer generally ends the application regardless of anything else. It typically includes conditions requiring ongoing oxygen, dialysis, a recent stroke or heart attack, certain cancers within a look-back period, and dementia.
- Time-boxed history questions, commonly looking back two years for treatment or hospitalisation and up to five for specific conditions.
- Pending or recommended procedures. A surgery your doctor has recommended but you have not scheduled still counts, and answering otherwise is a misrepresentation the carrier can act on later.
Two things follow. The look-back windows mean time itself changes the answer — a procedure that blocks you today may not in two years. And because the lists differ by carrier, the same person genuinely can be declined by one company and accepted by another in the same month.
If your window is open right now
Use it deliberately:
- Compare Plan G and Plan N on real quotes, not on premium alone. Plan N costs less monthly but adds copays of up to $20 per office visit and up to $50 per ER visit, and it does not cover the Part B excess charges Florida permits. Our Plan G vs Plan N calculator puts your own quotes and expected visits against the 2026 Part B deductible of $283 (CMS.gov) and shows which one actually costs less across a year.
| Plan G | Plan N | |
|---|---|---|
| Monthly premium | Higher | Lower |
| Part B deductible | You pay ($283 in 2026) | You pay ($283 in 2026) |
| Office visit copay | None | Up to $20 |
| Emergency room copay | None | Up to $50 |
| Part B excess charges | Covered | Not covered — relevant in Florida |
- Shop the carrier, not just the plan letter. Plan G is standardized — the benefits are identical by law from every company. The premium, the rate history and how sharply that premium climbs with age are not.
- Ask how the carrier rates. Attained-age policies start lower and rise with your age; issue-age and community-rated policies behave differently over twenty years. The cheapest premium at 65 is not reliably the cheapest premium at 78.
- Do it before the window closes, not in the last week of it. Applications take time, and an application that arrives late is just an application subject to underwriting.
The one-sentence version
Missing your Medicare Advantage window costs you a year. Missing this one can cost you the option permanently — so if you are inside it, treat the six months as the deadline it actually is.
If you would like the comparison run for your ZIP code with current carrier quotes, schedule a call. No cost, no obligation — and if your window is closing soon, say so when you book and we will prioritise it.