Medigap (Medicare Supplement Insurance) explained

Updated 2026-10-20 · Reviewed for accuracy by the EKO Labs team. Educational only; not medical advice.

Medigap, also called Medicare Supplement Insurance, is extra insurance you can buy from a private insurance company to help pay your share of out-of-pocket costs in Original Medicare, like copayments, coinsurance and deductibles. It is not part of the Medicare program and it is not a Medicare Advantage Plan. This guide explains how Medigap works, when it is easiest to buy, and what to check before you sign. It is general information, not legal or financial advice.

What Medigap is and what it covers

• Generally, you must have Original Medicare (Part A and Part B) to buy a Medigap policy.
• A Medigap policy covers one person. If you and your spouse both want Medigap, each of you needs your own policy.
• Medicare pays its share of the Medicare-approved amount first. Then your Medigap policy pays what you owe under the policy, and you are responsible for any costs that are left.
• Some Medigap policies also cover things Original Medicare does not, such as emergency care when you travel outside the U.S.

Medigap generally does not cover long-term care (like a nursing home), vision or dental care, hearing aids, glasses or private-duty nursing.

Standardized lettered plans

All Medigap policies are standardized. Policies with the same letter offer the same basic benefits no matter where you live or which company sells them. Most states offer up to 10 lettered plans: A, B, C, D, F, G, K, L, M and N. Not every plan is sold in every state, and not every company sells every plan. Price is the only difference between plans with the same letter sold by different companies, so compare the same letter (for example Plan G from one company with Plan G from another).

• Massachusetts, Minnesota and Wisconsin standardize Medigap in a different way.
• In some states you can buy a Medicare SELECT policy, which may cost less but can require you to use certain providers. If you buy one, you have the right to change your mind within 12 months and switch to a standard Medigap policy.
• Some companies offer a high-deductible option.

Your Medigap Open Enrollment Period

Under federal law you get a 6-month Medigap Open Enrollment Period. It starts the first month you have Medicare Part B and you are 65 or older. During this time:

• You can enroll in any Medigap policy a company sells. The company cannot refuse you or use medical underwriting to deny coverage or charge you more because of pre-existing health problems.
• Your coverage can start right away, except for coverage related to a pre-existing condition in some cases. Generally, a policy begins the first of the month after you apply, unless you ask for a different date.

This is a one-time period. It does not repeat every year like the Medicare Open Enrollment Period. After it ends, you may pay more, have fewer choices, or be denied a policy if you do not meet the company's medical underwriting rules.

Guaranteed issue rights

In certain situations a company cannot deny you a policy even after your Open Enrollment Period. These are called guaranteed issue rights (or Medigap protections). If one applies to you, apply no more than 63 days after your coverage ends, and keep copies of letters, notices or emails that prove your coverage ended. Your state may give you extra rights, so check with your State Insurance Department.

If you are under 65

If you have Medicare because of a disability or End-Stage Renal Disease (ESRD), federal law generally does not require insurance companies to sell you a Medigap policy before you turn 65. Some states do require it. Ask your State Insurance Department.

Medigap, Medicare Advantage and drug coverage

• Medigap vs. Medicare Advantage: a Medicare Advantage Plan (Part C) is another way to get your Medicare coverage. When you are getting started you can buy Medigap or join a Medicare Advantage Plan, but not both. Medigap cannot pay your Medicare Advantage copayments, deductibles or premiums.
• If you drop a Medigap policy to join a Medicare Advantage Plan for the first time, you get a single 12-month trial right period to get your Medigap policy back, if the same company still sells it. If you want to cancel Medigap, contact the company: most policies do not cancel on their own when you join a Medicare Advantage Plan.
• Drug coverage: Medigap plans sold after 2005 do not include prescription drug coverage. To get it, join a separate Medicare drug plan (Part D). If you buy Medigap and a drug plan from the same company, you may have two separate premium payments. See our guide on how to compare and join a Medicare drug plan.

What Medigap costs

• Premiums vary widely by company, plan and where you live. Each company decides how it sets its prices, which can affect what you pay now and later.
• You pay the Medigap company a monthly premium, and you still pay your monthly Medicare Part B premium. Medicare does not pay your Medigap premium.
• Premium amounts typically go up each year.
• Prices can depend on discounts (for example for non-smokers, paying yearly or paying automatically), medical underwriting when you have no guaranteed issue right, Medicare SELECT, and high-deductible options.
• The estimates you see online are estimates. Contact the company for an official quote.

Keeping your policy

Standardized Medigap policies renew automatically every year, even if you have health problems. A company can drop you only if you stop paying premiums, you were not truthful on the application, or the company goes bankrupt or out of business.

How to buy a Medigap policy

1. Decide which plan you want. Compare the benefits of each lettered plan and think about your current and future needs. You might not be able to switch later.
2. Pick a company. Buy only from a company licensed in your stateLicensed in your state U.S. doctors may treat patients only in states where they hold a license, so the doctor you see must be licensed where you live.. Get estimates from more than one company, ask your State Insurance Department about complaints against them, and ask your State Health Insurance Assistance Program (SHIP) for free help and, if available, a Medigap rate comparison guide for your state.
3. Get an official quote and apply. Fill out the application carefully and answer the medical questions. In your Open Enrollment Period, or with proof of a guaranteed issue right, the company cannot use your answers to deny you or change the price. The company must give you a clearly worded summary of the policy; read it and keep it.
4. Follow up. If you buy from an agent, get a receipt with the company's name, address and phone. If you have no documents 30 days after applying, call the company; after 60 days, call your State Insurance Department.

Changing your policy

• In most cases federal law does not give you a right to switch Medigap policies later unless you are in your 6-month Open Enrollment Period or have a guaranteed issue right.
• If you buy a policy during your Open Enrollment Period and change your mind, you can switch to a different one. You have a 30-day free look on the new policy. Do not cancel the first policy until you decide to keep the second; you pay both premiums for the month you have both.
• If you have had your current policy less than 6 months, the new policy may make you wait for pre-existing conditions.
• If you drop a Medigap policy, you might not be able to get it or any policy back later.

Illegal practices to watch for

Medicare.gov lists things that are illegal for someone selling Medigap, including:

• Pressuring you or lying to get you to switch companies or policies.
• Selling you a second Medigap policy when they know you already have one (unless you state in writing that you will cancel the old one).
• Selling you a Medicare Advantage Plan when you said you want to keep Original Medicare and buy Medigap.
• Claiming Medigap is part of Medicare or another federal program, or claiming to be a Medicare representative when working for a Medigap company.
• Asking about your family history or requiring a genetic test.
• Suggesting a policy is approved or recommended by the federal government.

If you think a federal law was broken, you can call the Inspector General's hotline (the number is on Medicare.gov), and you can contact your State Insurance Department.

Questions to ask before you buy

• Am I still inside my 6-month Medigap Open Enrollment Period, or do I have a guaranteed issue right?
• Which lettered plans are sold in my state, and which companies sell the plan I want?
• What is the official premium quote, how does the company set and change prices, and what discounts apply?
• Is this a standard plan or a Medicare SELECT policy with provider rules?
• How will I cover prescriptions (a separate Part D plan), dental, vision and hearing?
• Does the company have complaints on file with the State Insurance Department?

Our team can answer questions about your visit or prescription in Portuguese or English by phone. For help choosing a Medigap policy, contact your State Insurance Department or your SHIP.

Sources: Medicare.gov, Medicare Supplement Insurance (Medigap) pages: What's Medigap, Get Medigap Basics, How Medigap works, What Medigap covers, Get Medigap costs, Get ready to buy (Medigap Open Enrollment Period, guaranteed issue rights), How do I buy a Medigap policy, Can I change my Medigap policy, Illegal Medigap practices. Consulted October 2026. This guide is general information, not legal or financial advice.