Short answer
A Medigap policy is insurance sold by private insurance companies that helps pay your share of costs in Original Medicare.
Health insurance companies must clearly identify a Medigap policy as “Medicare Supplement Insurance.”
Generally, you need Part A and Part B to buy a Medigap policy.
The best time to buy is your Medigap Open Enrollment Period.
That is a 6-month period.
It starts when you are 65 or older and enrolled in Part B.
During that time, you may be able to buy any Medigap policy sold in your state, even if you have health problems.
After that period ends, you might not be able to buy a policy, and it may cost more.
This page does not say whether you can still buy a policy.
Only the insurance company, working under the rules on this page, can decide a real application.
This page is general information only. It is not financial advice and it is not benefits advice.
⚠️ Do not mix up these two “open enrollments”
The Medigap Open Enrollment Period is NOT the Medicare Open Enrollment period.
They are different things.
The Medicare Open Enrollment period is the yearly fall window when people can change their Medicare plans.
The Medigap Open Enrollment Period is different.
It is personal.
It happens one time.
It is your own 6-month window, and it starts when you are 65 or older and enrolled in Part B.
Read the timing rules below carefully.
They are the heart of this page.
What Medigap is
Medicare.gov says that if you chose Original Medicare, you may also want to buy a Medigap policy to help pay your share of costs.
Medigap works with Original Medicare.
It does not replace it.
Health insurance companies must clearly identify a Medigap policy as “Medicare Supplement Insurance.”
Generally, you need Part A and Part B to buy a Medigap policy.
Medicare.gov states the rule this way on its “How does Medicare work?” page: people with Medicare Advantage “can’t buy Medigap because it only works with Original Medicare.”
In most states, there are only a few Medigap standardized plans to pick from.
But there can be many insurance companies that sell policies for the same plan.
When to buy: the Medigap Open Enrollment Period
Medicare.gov says: “The best time to buy a Medigap policy is when you’re 65 (or older) and first get Part A and Part B.”
This is your Medigap Open Enrollment Period.
You have 6 months after your Part B coverage starts to buy a policy.
During this time, you may be able to buy any Medigap policy sold in your state, even if you have health problems.
Medicare.gov also states the protection this way: if you buy a Medigap policy during your Medigap Open Enrollment Period, the insurance company can’t use any answers to medical questions to deny you a Medigap policy or change the price.
The same protection applies if you give proof you have a guaranteed issue right, as explained below.
If you are under 65
Medicare.gov says: “If you’re under 65, you might not be able to buy a Medigap policy, or you may have to pay more.”
It says this is true even if you buy a Medigap policy in the first 6 months you have Medicare.
Can I buy a policy later?
After your Medigap Open Enrollment Period ends, you might not be able to buy a Medigap policy.
If you’re able to buy one or want to switch policies later, it may cost more.
After your Medigap Open Enrollment Period ends, insurance companies don’t have to sell you a Medigap policy, except in specific circumstances.
Medicare.gov calls these protections Medigap protections, or guaranteed issue rights.
If you qualify, you’ll need to give the company proof of your situation, like copies of letters, notices, or emails.
This page does not say whether one of these situations applies to you.
It only prints the rule as Medicare.gov states it.
The lettered plans
Medigap plans are standardized, and in most cases named by letters, like Plan G or Plan K.
Compare the benefits of each lettered plan to help you find one that meets your needs now and in the future.
The benefits in each lettered plan are the same, no matter which insurance company sells it.
Price is the only difference between policies with the same letter sold by different companies.
Costs can vary widely between companies.
That is why Medicare.gov tells readers to contact more than one company to get an estimate.
Not all plans are offered in every state.
And if a state offers a plan, not all insurance companies sell policies for it.
How to buy a Medigap policy
Medicare.gov lays out these steps.
Step 1 – Decide which plan you want
- Compare the benefits of each lettered plan.
- Think about your current and future health care needs. Decide which benefits you’ll need. Remember, you might not be able to switch Medigap policies later.
- Select the plan that meets your needs.
Step 2 – Pick your policy
- Find insurance companies selling the standardized plan you want and talk to them. You can buy a Medigap policy from any insurance company that’s licensed in your state to sell one.
- As you shop for a policy, be sure you’re comparing the same lettered plan offered by different insurance companies. For example, compare Plan A from one company with Plan A from another company.
- Shop by price. Price is the only difference between policies with the same letter sold by different companies. Since costs can vary widely between companies, contact more than one company that sells Medigap policies in your state to get an estimate.
- Call your State Insurance Department for a list of companies selling policies in your state. Ask if they have any complaints against insurance companies.
- Contact your local State Health Insurance Assistance Program (SHIP) to get free help choosing an insurance company in your area. SHIPs aren’t connected to any insurance company or health plan. SHIPs are state programs that give free local health insurance counseling to people with Medicare and their families. Ask your SHIP if they have a “Medigap rate comparison shopping guide” for your state.
Step 3 – Contact the company
- Get an official quote from the company.
- Read your Medigap policy carefully and ask questions if you don’t understand it.
- When you’re ready to buy, contact the company and fill out their application.
- The insurance company must give you a clearly worded summary of your Medigap policy. Make sure you read it carefully and keep it for your files. If you don’t understand it, ask questions.
Step 4 – Apply for the plan
- Fill out the application carefully and completely, and answer any medical questions.
- If you buy a Medigap policy during your Medigap Open Enrollment Period or give proof you have a guaranteed issue right, the insurance company can’t use any answers to medical questions to deny you a Medigap policy or change the price.
- The insurance company must give you a clearly worded summary of your Medigap policy. Read it carefully and keep it for your files.
- If you buy your policy from an agent, get a receipt with the insurance company’s name, address, and phone number for your records.
After you buy a policy
Generally, Medigap policies begin the first of the month after you apply.
If you already have a Medigap policy, ask for your new Medigap policy to become effective when your old Medigap policy coverage ends.
If it’s been 30 days and you didn’t get any documents from your Medigap policy, like your Medigap card or proof of insurance, call your insurance company.
If it’s been 60 days and you still don’t have any documents from your Medigap policy, call your State Insurance Department.
Every Medigap policy must follow federal and state laws designed to protect you.
This page never asks you for any personal information.
There is no form on this page.
Give your information only to the insurance company you choose, through the steps on this page.
Sources
Everything on this page comes from the official sources below, each read in full. All three pages are from Medicare.gov.
- Medicare.gov — Buying a Medigap policy — https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/buying-a-medigap-policy
- Medicare.gov — How do I buy a Medigap policy? — https://www.medicare.gov/health-drug-plans/medigap/ready-to-buy/how
- Medicare.gov — How does Medicare work? — https://www.medicare.gov/basics/get-started-with-medicare/medicare-basics/how-does-medicare-work
The Medicare Advantage point on this page comes from the third source. The first two sources do not state it.
Checked November 2, 2026.
This page is general information only. It is not financial advice and it is not benefits advice.