Direct answer: Medigap open enrollment at 65 is a one-time, 6-month window. It starts the first month you are 65 or older and enrolled in Part B. During those months, a company selling Medigap in your state cannot turn you down or charge you more because of your health.
This decision is hard to undo. Buy a Medigap policy inside your Medigap open enrollment at 65, and your health does not affect the sale. Wait too long, and in most states the company can ask about your health and say no.
The window does not come back each fall. It happens once, and the clock runs whether you shop or not.
If you are reading this at the kitchen table with a pile of Medicare mail, take a breath. Six months is enough time if you take the steps in order.
In my 18 years in insurance marketing, I have seen ads blur this window with the fall sign-up season. They are two different things. Mixing them up can lock you out of the plan you wanted.
What is Medigap, and how is this window different from the others?
Medigap is a private policy that works next to Original Medicare. It helps pay costs Medicare leaves to you, like the Part A hospital deductible and the 20% you owe under Part B. It does not work with Medicare Advantage.
Medigap plans come in letters, like G and N. Benefits for the same letter are the same at every company in most states. Prices are not. Two companies can charge very different amounts for the same Plan G.
Medicare has several sign-up windows. Each one does a different job.
Swipe sideways to see every column.
| Window | When it happens | What it is for | Can Medigap ask health questions? |
|---|---|---|---|
| Medigap open enrollment | 6 months, starting the first month you are 65+ and have Part B | Buy any Medigap policy sold in your state | No, with limited exceptions |
| Initial Enrollment Period | Around your 65th birthday | Sign up for Part A and Part B | Not a Medigap window |
| Fall Open Enrollment | Each fall, on dates Medicare sets | Change Advantage or Part D plans | Yes, in most states |
| Medicare Advantage Open Enrollment | Early each year | Switch Advantage plans or return to Original Medicare | Yes, in most states |
That last column holds the main lesson. Only one row protects you from health questions, and you get it once.
Why does the 6-month window exist?
Without rules, Medigap companies could price every buyer by health. People with diabetes, heart trouble, or a cancer history might pay far more or get turned away.
Federal rules set aside one protected window for each new Medicare enrollee. During it, you can buy any Medigap policy sold in your state. The company cannot deny you or raise your price over health problems, as Medicare.gov explains on its page about when to buy Medigap.
There is one exception to know. If you did not have other health coverage before Medicare, a company may make you wait before it pays for a health problem you already had. Ask about this before you apply.
Once the window closes, most states let companies use medical underwriting. That means health questions, possible higher prices, and possible denials. A few states give people more rights. Your State Health Insurance Assistance Program (SHIP) can tell you your state’s rules.
What do the 2026 numbers say about the gap Medigap fills?
Original Medicare has no yearly limit on what you pay out of pocket. Here are the 2026 figures from the Medicare.gov 2026 cost fact sheet.
Swipe sideways to see every column.
| 2026 cost under Original Medicare | Amount |
|---|---|
| Part B monthly premium (standard) | $202.90 |
| Part B yearly deductible | $283 |
| Part B coinsurance after deductible | 20% |
| Part A hospital deductible | $1,736 per benefit period |
| Hospital days 61 to 90 | $434 per day |
| Skilled nursing days 21 to 100 | $217 per day |
Here is a worked example. Say you have two hospital stays in one year, in two separate benefit periods. That is two Part A deductibles, or $3,472.
Now add a 40-day skilled nursing stay after one of those stays. Days 1 to 20 cost $0. Days 21 to 40 are 20 days at $217, or $4,340.
Then add $10,000 in outpatient care after your Part B deductible. Your 20% share is $2,000.
Without other coverage, that one rough year costs $9,812 on top of your premiums. You also pay the $283 Part B deductible. Your Part B premium of $202.90 a month adds $2,434.80 for the year, and Medigap does not pay it.
Plan G would cover the Part A deductibles, the skilled nursing coinsurance, and the 20% Part B share in this example. You would still pay the $283 Part B deductible. Plan N covers those same big items, but it has some copays and does not cover excess charges. See Medigap Plan G vs Plan N for the side-by-side.
If your income is higher, your Part B premium may be higher too. In 2026, a single filer with 2024 income above $109,000 pays at least $284.10 a month. Read Medicare Part B premiums and IRMAA for the full table.
The fine print: how the clock starts without you
The clock follows Part B, not your birthday
Say you turn 65 in May and your Part B starts May 1. Your Medigap window runs May through October. Circle the last day on your calendar.
Signing up for Part B too early can waste the window
If you still have health coverage from your own job or your spouse’s job, you may be able to delay Part B. Your Medigap window then waits until Part B starts.
Signing up for Part B “just in case” starts the clock anyway. You cannot restart it later. Read Medicare and working past 65 before you make that move.
Under 65 is a different set of rules
Federal law does not require companies to sell Medigap to people under 65 on Medicare. Some states do require it. When you turn 65, you get your own 6-month window. See Medicare under 65 for the disability path.
Medigap does not cover drugs
You still need Part D or other drug coverage that counts as creditable. If you go without it, a late penalty can follow you. Start with Medicare Part D drug coverage in 2026.
Should everyone lock in Medigap at 65?
The common advice is to buy Plan G at 65 and be done. That advice fits many people, but not all of them.
If money is tight
Medigap means a second premium every month on top of $202.90. If your income is limited, check whether you qualify for state help first. A Medicare Savings Program can pay your Part B premium. See our guide to Extra Help and Medicare Savings Programs.
If you choose Medicare Advantage at 65
Some people start with Advantage for the low premium. Medicare offers a limited trial right that lets some first-time Advantage members return to Medigap without health questions. The conditions are narrow, so read them on Medicare.gov before you count on them.
If you feel healthy today
This is where I push back hardest. Your window protects the person you will be at 75 or 80. Skipping Medigap because you feel fine now leaves you unprotected later. Health questions show up after a diagnosis, when you can least afford a denial.
If you are still working with good coverage
Waiting may be the smart move. Your window will start when your Part B does.
Where the money goes
From the lead-generation side, I can tell you that turning 65 is one of the most valuable moments in Medicare marketing. Your name, age, and ZIP code land on mailing lists months before your birthday. That is why the mail and calls pile up.
Insurance companies pay agents a commission. You do not pay the agent directly. Pay can differ by product and by company, and that can tilt which plan an agent talks about first.
Because Plan G is the same at every company in most states, the real choice is price and how that price rises. Companies price Medigap in different ways. Some base it on your age when you buy, and some raise it as you age. The Medicare guide to choosing a Medigap policy explains each method.
Be wary of mailers with fake Medicare logos and calls that push you to act today. Your window is six months long, and a real offer will still be there tomorrow.
Related: compare paths in Medigap vs Medicare Advantage, and learn the calendar in Medicare enrollment windows and penalties.
Seven moves inside your six months
- Find your Part B start date. It is on your red, white and blue Medicare card. Write down the date your window closes.
- Choose your path. Decide between Original Medicare with Medigap or Medicare Advantage. Think about your doctors, your travel, and your budget.
- Pick a letter. Use the Medicare.gov Medigap plan finder to see the letters sold in your ZIP code.
- Get quotes from at least three companies for that same letter. Same benefits, different prices.
- Ask each company two questions. How do you set your price as I age? How much have rates gone up in recent years?
- Add drug coverage. Pick a Part D plan so you avoid a late penalty.
- Apply early and keep copies. Ask how far ahead the company takes applications so coverage starts on time. Save every page in one folder.
What not to do
Don’t cancel any current coverage until your new policy is in force. Don’t drop a Medigap policy to “try” Advantage until you have read the trial-right rules. And don’t sign anything on the first call.
Frequently asked questions
Can I buy Medigap during fall Open Enrollment without health questions?
In most states, no. Fall Open Enrollment is for changing Medicare Advantage and Part D plans. It does not give you new Medigap rights. Outside your 6-month window and a few special situations, Medigap companies can ask about your health. A few states have extra rules, so check with your local SHIP office.
What if I already missed my 6-month window?
You can still apply, but the company may ask health questions, charge more, or deny you. Some special situations give you a protected right to buy, such as losing certain other coverage. Your state may also have its own rules. A free SHIP counselor can look at your situation and tell you which options apply.
Does the window start on my 65th birthday?
Not always. It starts the first month you are both 65 or older and enrolled in Part B. If you delay Part B because you still have job-based coverage, the window waits. If you sign up for Part B early, the clock starts then, even if you do not need Medigap yet.
Can I get Medigap before 65 if I have Medicare through disability?
Federal law does not require companies to sell Medigap to people under 65. Some states do require it, and prices for younger buyers may be higher. When you turn 65, you get your own 6-month Medigap window with full protections. Check your state’s rules through SHIP or your state insurance department.
Does Medigap pay for my prescriptions?
No. Medigap policies sold today do not include drug coverage. You need a separate Part D plan or other drug coverage that Medicare counts as creditable. If you go too long without it, you may owe a late penalty for as long as you have Part D. Shop for Part D during the same months.
Your next step
Find your Medicare card and write down your Part B start date. Count six months forward and mark the last day. Then call your State Health Insurance Assistance Program for free help comparing plans before any sales call. For yearly reviews after this, keep our Medicare OEP and AEP checklist handy.
Sources