Medigap Eligibility Calculator: Whether You Can Still Buy a Policy, and How Many Days Are Left
The Medicare Advantage sales call does not raise the question that matters most: if you take this plan, can you get back to a Medigap policy later? For most people, after one six-month window closes, the answer is no — and nobody starts that clock for you. This page works out where you stand today.
You are inside your one-time window
You are inside your Medigap Open Enrollment Period, with about 4.0 of the six months left. Right now no insurer may refuse you, charge you more for your health, or make you answer a health question. This period is one time only and it does not repeat. You may buy any Medigap policy sold in your state, except Plans C and F, which are closed to anyone new to Medicare from 1 January 2020. A pre-existing condition waiting period of up to 6 months could apply, because the coverage you have had does not fully waive it. This is the federal floor only. Several states grant rights beyond it — annual or continuous guaranteed issue, birthday rules, and windows for people under 65 — so confirm with your State Health Insurance Assistance Program at shiphelp.org or your State Insurance Department before acting on a "no" here.
This is the federal floor — your state may give you more
Everything above is federal law, which is the minimum every state must provide. Some states add continuous or annual guaranteed issue, birthday rules that let you switch each year, and rights for people under 65. None of those are modelled here, so a result of “no federal right” is a reason to ask, not a reason to stop.
Your State Health Insurance Assistance Program gives free Medicare counselling and sells nothing. If you are denied a policy in a situation where you believe a right applies, contact your State Insurance Department.
Your one-time window
Six months from the first month you have Part B at 65. It does not repeat.
This period runs six months from the first month you have Part B and are 65 or older, and it does not repeat.
The right you described
Each of the seven situations carries its own window.
Your trial-right clock
The deadline people lose without noticing.
What you may buy
Cover is standardized by law, so a plan letter means the same thing at every insurer.
Any Medigap policy sold in your state, except Plans C and F.
What to do next
Steps that follow from your answers.
- Apply while this window is open. Inside it no insurer may ask a health question, decline you, or charge you more because of your health — and this window does not come back.
- Compare the same plan letter across insurers. The cover is standardized by law, so for a given letter the difference between companies is price and service, not benefits.
- Ask any insurer about the pre-existing condition waiting period: up to 6 months could apply on your figures. Six months of continuous prior coverage removes it, so tell them about coverage you have had.
All seven federal guaranteed issue situations
Read straight from the bound CMS guide.
| # | The situation | What you may buy | Opens | Closes |
|---|---|---|---|---|
| 1 | Your Medicare Advantage plan is leaving Medicare, stops serving your area, you move out of its service area, or its network changes significantly | Plans A, B, D, G | 60 days before it ends | 63 days after |
| 2 | You have Original Medicare and an employer group health plan (including retiree, COBRA or union coverage) that pays after Medicare, and that plan is ending | Plans A, B, D, G | When it ends | 63 days after |
| 3 | You have Original Medicare and a Medicare SELECT policy, and you move out of its service area | Plans A, B, D, G | 60 days before it ends | 63 days after |
| 4 | Trial right: you joined a Medicare Advantage plan or PACE when you were first eligible for Part A at 65, and within the first year you want to switch to Original Medicare | Any policy in your state | 60 days before it ends | 63 days after |
| 5 | Trial right: you dropped a Medigap policy to join a Medicare Advantage plan or Medicare SELECT for the first time, you have been in the plan less than a year, and you want your Medigap policy back | The policy you had, or the subset | 60 days before it ends | 63 days after |
| 6 | Your Medigap insurance company goes bankrupt and you lose coverage, or your Medigap coverage ends through no fault of your own | Plans A, B, D, G | When it ends | 63 days after |
| 7 | You leave a Medicare Advantage plan or drop a Medigap policy because the company has not followed the rules, or it misled you | Plans A, B, D, G | When it ends | 63 days after |
In every one of these an insurer must sell to you, must cover your pre-existing conditions with no waiting period, and may not charge you more because of your health. If more than one applies, you may choose whichever suits you best.
How this works
Federal law gives you one six-month Medigap Open Enrollment Period. It begins the first month you have Part B and are 65 or older, and it does not repeat. Inside it, no insurer may refuse you, charge you more for your health, or ask a health question. Outside it, an insurer may do all three — unless one of seven specific situations gives you a guaranteed issue right, and each of those carries a deadline measured in days. Two are trial rights that expire quietly at twelve months. Enter your dates and this page tells you which door is open and how long it stays open.
Someone who turned 65 in March, took Part B the same month, and is deciding in May is four months into their six-month window: about sixty days remain, and every policy sold in their state must be offered to them at their age rate with no health questions. Someone who took an Advantage plan at 65 and is now 71 has no federal right at all — unless their plan is leaving Medicare, their employer coverage is ending, or one of the other five situations applies, in which case they have sixty-three days from the day that coverage ends.
The two clocks that catch people are the trial right, which ends at twelve months in the plan, and the sixty-three days after coverage ends. Both run silently, and neither is anyone's job to remind you about.
Seven ways back, each with a deadline
Outside that window, an insurer may decline you outright. Federal law creates seven situations where it may not — CMS calls them guaranteed issue rights, and in each the insurer must sell, must cover your pre-existing conditions with no waiting period, and may not charge you more for your health.
Every one of them expires 63 days after the coverage ends. Four also open 60 days before it ends, which gives you time to line up the replacement; three do not open until the coverage actually ends. That difference matters, and this page reads it per situation rather than assuming.
If more than one applies, CMS says you may choose whichever suits you best.
Trial rights expire in silence
Two of the seven are trial rights, and they are the ones people lose without noticing. Take a Medicare Advantage plan when you are first eligible at 65, and you have twelve months to change your mind and buy any Medigap policy sold in your state. Drop a Medigap policy for Advantage for the first time, and you have twelve months to buy it back.
Month thirteen is a different world: the same person, the same health, no right at all. Nothing arrives in the post to tell you the door has shut.
If you are inside one of these, the twelve-month limit and the 63-day limit both apply, and the earlier one wins.
What medical underwriting actually means
Outside a window and without a right, buying Medigap means answering health questions. An insurer may decline you, exclude a condition, or charge more — and a diagnosis you already have is exactly what makes the answer no.
This is the asymmetry that makes the decision at 65 so consequential. Medicare Advantage must take you every year during the annual election period regardless of health. Medigap generally does not, once your window has passed.
It is why 'you can always switch later' is the single most expensive thing a healthy 65-year-old can believe.
Plans C and F, and why the date is not the application date
Plans C and F are not available to people who became eligible for Medicare on or after 1 January 2020. Those plans covered the Part B deductible, which the law now prevents new enrollees from buying cover for.
The test is when you first became eligible, not when you apply. Someone who was eligible before 2020 but has not yet signed up may still be able to buy Plan C or F, which is why this page asks about eligibility rather than dates.
People new to Medicare from 2020 have Plan D and Plan G in their place, which are the same cover minus that deductible.
This is the federal floor, not the whole answer
Everything above is federal law, and federal law is the minimum. Several states give more: continuous or annual guaranteed issue, birthday rules that let you switch within a window each year, and rights for people under 65 that federal law does not provide.
This page does not model any of them, and it never presents a federal 'no' as a final answer. If it tells you no federal right applies, that is a reason to call your State Health Insurance Assistance Program, not a reason to give up.
SHIP counselling is free, available in every state, and sells nothing. Find yours at shiphelp.org. If you are denied a policy in a situation where you believe a right applies, your State Insurance Department is the regulator.
The seven federal guaranteed issue situations
Outside your one-time window, these are the situations in which an insurer must sell to you. Note that the window does not open early in every case — three of the seven begin only when the coverage ends.
| # | The situation | What you may buy | Window opens | Window closes |
|---|---|---|---|---|
| 1 | Your Medicare Advantage plan is leaving Medicare, stops serving your area, you move out of its service area… | Plans A, B, C*, D, F*, G* | 60 days before | 63 days after |
| 2 | You have Original Medicare and an employer group health plan (including retiree, COBRA or union coverage) t… | Plans A, B, C*, D, F*, G* | Not until it ends | 63 days after |
| 3 | You have Original Medicare and a Medicare SELECT policy, and you move out of its service area | Plans A, B, C*, D, F*, G* | 60 days before | 63 days after |
| 4 | Trial right: you joined a Medicare Advantage plan or PACE when you were first eligible for Part A at 65, an… | Any policy sold in your state | 60 days before | 63 days after |
| 5 | Trial right: you dropped a Medigap policy to join a Medicare Advantage plan or Medicare SELECT for the firs… | The policy you had, or the subset | 60 days before | 63 days after |
| 6 | Your Medigap insurance company goes bankrupt and you lose coverage, or your Medigap coverage ends through n… | Plans A, B, C*, D, F*, G* | Not until it ends | 63 days after |
| 7 | You leave a Medicare Advantage plan or drop a Medigap policy because the company has not followed the rules… | Plans A, B, C*, D, F*, G* | Not until it ends | 63 days after |
*Plans C and F only if you first became eligible for Medicare before 1 January 2020. In every situation the insurer must also cover your pre-existing conditions with no waiting period and may not charge you more because of your health. Your state may grant further rights beyond these.
Generated from the bound CMS dataset (Product No. 02110, March 2026) and locked by golden tests.
Assumptions & Limitations
This tool assumes:
- You are aged 65 or over. Under 65, whether a Medigap policy is available at all is set by your state, not by federal law.
- Months are counted whole: 'months since Part B started' means completed months, where zero is the month it began.
- A qualifying event dated in the future is treated as a right that has not opened yet, not as a refusal.
- Trial rights are tested on how long you have been in the plan, which is the twelve-month limit CMS states.
- Creditable coverage is credited month for month up to six months, and is disregarded entirely if any break exceeded 63 days.
- Plan C and Plan F availability turns on when you first became eligible for Medicare, not on when you apply.
It does not cover:
- This models the FEDERAL FLOOR ONLY. Several states grant rights beyond it — annual or continuous guaranteed issue, birthday rules, and windows for people under 65 — and none of them are in this engine. A result of 'no federal right' is not a finding that you have no right.
- It does not tell you whether a particular insurer will accept you, what any policy costs, or which plan letter suits you.
- It does not model Medicare Advantage enrolment periods, Part D, Medicaid interaction, or employer plan rules beyond the guaranteed issue trigger.
- Massachusetts, Minnesota and Wisconsin standardize Medigap policies differently, so the plan letters reported here do not describe what is sold in those states.
- CMS notes that trial rights may last an extra twelve months in certain circumstances; that extension is not modelled, so a result near the limit is worth checking with your State Insurance Department.
- It is not insurance advice and not a substitute for your State Health Insurance Assistance Program, which is free and sells nothing.
Evidence, sources and editorial review
Medigap Eligibility Calculator: Whether You Can Still Buy a Policy, and How Many Days Are Left groups its evidence and methodology review here so sources, assumptions and responsibility can be checked together.
Methodology
Every rule here comes from CMS Product No. 02110, 'Choosing a Medigap Policy' (March 2026), bound as a provenance-tracked dataset that the engine reads at run time rather than restating in code. The Medigap Open Enrollment Period runs for six months from the first month you have Part B and are 65 or older, and it does not repeat; months elapsed are subtracted from it to give the months remaining. Outside that period the engine tests the qualifying event you describe against the seven federal guaranteed issue situations, each of which carries its own window: some open sixty days before the coverage ends and some not until it ends, and all close sixty-three days after. Those per-situation windows are read from the dataset, not assumed from the general figure, because they differ. A qualifying event that has not happened yet is reported as a right that is coming rather than as a refusal. Two of the seven are trial rights, which additionally end once you have been in the plan twelve months. Which policies a right covers is likewise read per situation. Plans C and F are excluded for people first eligible for Medicare from 1 January 2020 — a test on eligibility, never on the date you apply. The pre-existing condition waiting period starts at six months, is removed entirely by a guaranteed issue right, and is otherwise credited month for month against continuous prior coverage, provided no break exceeded sixty-three days. The engine models the federal floor only; state law adds rights it does not contain, and every result says so. All figures are locked by golden tests that run on each build.
Reviewed according to the CalcDomain Editorial Policy & Calculator Methodology. We document formulas, edge cases, sources, update dates, and correction paths for calculator pages.
If a rule or a source here is wrong, use the feedback control on this page. Corrections are made against the CMS guide, the golden tests are updated in the same change, and the version history below records what moved.
Updated
References & Authoritative Sources
- Centers for Medicare & Medicaid Services — Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare (CMS Product No. 02110) · consulted August 28, 2026 · Every rule on this page: the open enrollment period (pages 10-11) and the guaranteed issue situations (pages 15-19). Developed jointly by CMS and the NAIC.
- Medicare.gov — Medicare Supplement Insurance (Medigap) · consulted August 28, 2026 · The official consumer pages behind the guide.
- State Health Insurance Assistance Programs — SHIP — free, unbiased Medicare counselling in your state · consulted August 28, 2026 · Where to confirm the rights your state adds to the federal floor. SHIP counsellors sell nothing.
- National Association of Insurance Commissioners — State Insurance Department directory · consulted August 28, 2026 · The regulator to contact if you are denied a policy in a situation where a right should apply.
Data Source
The bound CMS guide supplies every rule the engine applies — the length of the open enrollment period, the seven guaranteed issue situations with their individual windows and plan subsets, the trial-right limit and the pre-existing condition rules.
Frequently Asked Questions
Can I switch from Medicare Advantage to Medigap later?
Only if a window is open. Your one-time six-month Medigap Open Enrollment Period runs from the first month you have Part B at 65 and does not repeat. After it, you need one of seven federal guaranteed issue situations — for example your plan leaving Medicare, or a trial right if you took Advantage when first eligible and are still within twelve months. Otherwise an insurer may ask about your health and decline you. Several states are more generous, so check with your SHIP before treating a federal 'no' as final.
How long is the Medigap Open Enrollment Period, and when does it start?
Six months, starting the first month you have Medicare Part B and are 65 or older. CMS is explicit that it is one-time and does not repeat every year. Inside it, an insurer must sell you any policy it offers in your state, cannot use medical underwriting, and cannot charge you more because of your health.
What is a guaranteed issue right?
A situation where federal law forces an insurer to sell to you outside your open enrollment window. In each, the insurer must sell you a policy, must cover all your pre-existing conditions with no waiting period, and cannot charge you more because of past or present health problems. There are seven such situations, each with its own deadline — all of them 63 days after the coverage ends, and four of them opening 60 days before.
What is a Medigap trial right?
Two of the seven rights are trial rights. If you joined a Medicare Advantage plan or PACE when you were first eligible for Part A at 65, you have twelve months to switch to Original Medicare and buy any Medigap policy sold in your state. If you dropped a Medigap policy to join Advantage for the first time, you have twelve months to buy that policy back. Both end at twelve months in the plan, and neither sends you a reminder.
I missed the 63-day window. What now?
Under federal law that particular right has expired, and an insurer may underwrite you. That is not necessarily the end: another situation may apply, your state may grant rights the federal floor does not, and some states allow switching every year or around your birthday. Call your State Health Insurance Assistance Program at shiphelp.org — the counselling is free and they sell nothing.
Why can't I buy Plan C or Plan F?
They are closed to people who first became eligible for Medicare on or after 1 January 2020, because those plans covered the Part B deductible. The test is your eligibility date, not your application date, so someone eligible before 2020 who has not yet signed up may still be able to buy them. Plans D and G are the equivalents for everyone else.
Will I have to wait for a pre-existing condition to be covered?
Possibly up to six months, and only for a condition treated or diagnosed in the six months before the policy starts. A guaranteed issue right removes the waiting period completely. Otherwise six months of continuous prior creditable coverage removes it, credited month for month, provided no break in that coverage was longer than 63 days. Original Medicare still covers the condition throughout; the waiting period is only about the Medigap policy's share.
Does this page cover my state's rules?
No, and that is deliberate. It models federal law, which is the minimum every state must provide. Some states add continuous or annual guaranteed issue, birthday rules, or rights for people under 65. Encoding fifty-one sets of separately published regulation without verifying each against its source would risk telling you that you have no right when you do, so this page reports the federal floor, says so on every result, and points you to your SHIP and State Insurance Department.
Related Calculators
One window, six months, once
Your Medigap Open Enrollment Period starts the first month you have Medicare Part B and are 65 or older, runs for six months, and never repeats. CMS states it plainly: 'This is a one-time enrollment period; it doesn't repeat every year.'
Inside it an insurer must sell you any Medigap policy it offers in your state, cannot use medical underwriting, and cannot charge you more because of your health. That is the strongest position you will ever be in, and for most people it is over before they know it existed.
Because it starts with Part B, delaying Part B while you have employer coverage delays the window rather than wasting it. That is the one common case where waiting is the right move.
Suggest an improvement
Found a calculation issue, outdated source, unclear assumption, or missing edge case? Send a short note so we can review it.
Update history
Last updated .
| Date | Version | Change |
|---|---|---|
| 2026-08-28 | 1.0 | First release: one-time open enrollment clock, all seven federal guaranteed issue situations with per-situation windows read from the CMS dataset, trial-right limit, plan availability, Plan C/F eligibility and the pre-existing condition waiting period |