Medicare Supplement Plans: How Medigap Works & What It Covers

Original Medicare can cover a large share of your healthcare costs, but it does not pay every expense.

That is where Medicare Supplement plans, also called Medigap, come in. These private insurance policies work alongside Original Medicare and can help pay certain costs that Medicare leaves behind, including eligible deductibles, coinsurance, and copayments.

For someone new to Medicare, Medigap can raise several questions. How does it actually work? Which lettered plan should you consider? What does it cost? When can you buy it? Do Medigap plans include prescription coverage? And can you use any doctor?

The answers become much clearer once you separate Medigap from Medicare Advantage and understand how the lettered plans are structured.

AI Overview: What Is Medicare Supplement Insurance?

Medicare Supplement Insurance, commonly called Medigap, is private insurance designed to help pay some of the out-of-pocket costs left by Original Medicare.

You generally need both Medicare Part A and Part B to buy a Medigap policy. Medigap does not replace Original Medicare. Instead, Medicare generally pays its share first, and the Medigap policy may then pay some of the remaining eligible costs based on the plan you purchased.

Medigap plans are standardized by letter in most states. A plan with the same letter generally provides the same basic benefits regardless of the insurance company selling it. Premiums can differ between companies.

Medigap does not include prescription drug coverage. If you want Medicare Part D coverage while using Original Medicare and Medigap, you generally need a separate Medicare drug plan.

TL;DR: Medicare Supplement Plans at a Glance

How Do Medicare Supplement Plans Work?

Medigap is designed to work alongside Original Medicare.

Here is the basic process:

For example, Original Medicare Part B generally leaves you responsible for a portion of covered outpatient costs after the applicable deductible. A Medigap plan may help cover that cost-sharing depending on the plan. That can make the overall cost structure easier to understand before you receive care.

You Still Have Original Medicare

This is an important distinction. When you buy Medigap, you do not leave Original Medicare.

You continue using your Medicare card, and Medicare remains your primary coverage for Medicare-covered Part A and Part B services. The Medigap policy is secondary coverage that helps with eligible costs according to its benefits.

That is different from Medicare Advantage, where you receive your Part A and Part B benefits through a Medicare-approved private plan.

What Do Medigap Plans Cover?

Different lettered plans cover different combinations of Medicare cost-sharing. Depending on the plan, Medigap may help with expenses such as:

• Part A hospital coinsurance
• Part B coinsurance or copayments
• Part A deductible
• Skilled nursing facility coinsurance
• Part A hospice coinsurance or copayments
• The first three pints of blood
• Certain foreign travel emergency costs

The exact benefits depend on the plan letter. Some plans are more comprehensive than others, while others cover a smaller share of costs in exchange for a different premium structure. That is why comparing the lettered plans matters before focusing on the insurance company.

What Does Medigap Not Cover?

Medigap is not designed to cover every healthcare expense. Medicare guidelines state that Medigap policies generally do not cover:

• Long-term care
• Routine dental care
• Vision care
• Hearing aids
• Eyeglasses
• Private-duty nursing
• Prescription drugs

Some Medigap policies provide limited foreign travel emergency coverage, but the details depend on the plan.

Prescription coverage is particularly important to understand. If you choose Original Medicare plus Medigap and want Medicare prescription drug coverage, you generally need a separate Part D plan.

How Are Medigap Plans Standardized?

One of the most useful things to understand about Medigap is the letter system.

In most states, Medigap plans are standardized and identified by letters such as A, B, C, D, F, G, K, L, M, and N. Plans with the same letter generally offer the same basic benefits regardless of the company selling them.

That makes one part of the comparison easier. For example, if you are reviewing Plan G from two different companies, the standardized benefits are generally the same. What can vary is the premium and other company-specific factors.

Massachusetts, Minnesota, and Wisconsin standardize Medigap differently, so people living in those states should check their state's rules.

A Simple Way to Think About the Letter System

The chart is only a starting point. Each plan letter has a defined set of benefits, so review the official benefit chart before choosing a policy.

Plan G vs. Plan N: What Is the Difference?

Plan G and Plan N are two Medigap options people often investigate when they are new to Medicare. The important thing is not to assume one is automatically right for everyone.

Plan G

Plan G generally covers a broad range of Medicare cost-sharing, but it does not cover the Part B deductible for people who are newly eligible for Medicare. In 2026, that deductible is $283.

After the applicable Part B deductible, Plan G covers many of the remaining standardized benefits listed for the plan.

Plan N

Plan N also provides substantial Medigap coverage but includes some cost-sharing.

For 2026, Plan N can require a copayment of up to $20 for certain office visits and up to $50 for emergency room visits when the emergency room visit does not result in an inpatient admission. Plan N also has different rules regarding Part B excess charges.

The choice between these types of coverage comes down to the plan's benefits, premium, and the way you prefer to handle healthcare costs.

Why the Medigap Open Enrollment Period Matters

Timing is one of the most important parts of buying Medigap.

Your Medigap Open Enrollment Period is a one-time six-month period that starts when you are 65 or older and your Part B coverage begins. During this period, you generally have broader rights to buy Medigap coverage without medical underwriting.

This is different from Medicare Open Enrollment, which occurs every year from October 15 through December 7. Your Medigap Open Enrollment Period does not repeat every year. That distinction is easy to miss.

Why Does This Six-Month Window Matter?

Outside the Medigap Open Enrollment Period, an insurance company may be able to use medical underwriting unless you have a specific guaranteed issue right or other protection. Depending on your situation and state law, you could face:

• Higher premiums
• Fewer available policy choices
• A denial of coverage

This is why understanding the timing before buying a policy can be important.

What If You Delay Part B Because You Are Still Working?

Your Medigap enrollment window is connected to your Part B start date.

If you delay Part B because you have group health plan coverage based on current employment, your six-month Medigap Open Enrollment Period generally does not begin until you actually get Part B and are 65 or older.

That can be different from someone who enrolls in Part B at 65. Before delaying Part B, confirm how your employer coverage works with Medicare and understand what happens to your future Medigap enrollment opportunity.

What Are Guaranteed Issue Rights?

There are certain situations where federal law gives you a guaranteed issue right to buy a Medigap policy.

These protections can apply in specific circumstances, such as losing certain types of coverage or leaving a Medicare Advantage plan under qualifying conditions.

When guaranteed issue rights apply, an insurance company generally cannot deny you a Medigap policy or use your health history to change the basic availability of the policy in the way it might outside a protected period. The specific policy choices and deadlines depend on the situation.

State laws may also provide additional Medigap protections. Because the rules are situation-specific, it is important to check your individual circumstances and state requirements.

How Much Do Medigap Plans Cost?

There is no single Medigap premium that applies to everyone.

Insurance companies set their own premiums, and the amount can depend on factors such as the plan you choose, where you live, your age, and the way the insurer prices its policies.

Medicare identifies three common pricing methods:

Understanding the pricing method can help you look beyond the first monthly quote.

What Else Should You Pay for With Medigap?

A Medigap premium is only one part of the overall Medicare budget.

You still generally pay your Medicare Part B premium. In 2026, the standard Part B premium is $202.90 per month, although some people pay more based on income.

If you want prescription drug coverage, you generally pay separately for a Part D plan as well. So someone using Original Medicare with Medigap and Part D may have three separate monthly premiums:

That does not necessarily mean higher or lower total healthcare spending for every person. It simply describes how this coverage structure is commonly paid for.

Medigap vs. Medicare Advantage: What's the Difference?

This is one of the most important comparisons for people approaching Medicare.

Medigap and Medicare Advantage are not two policies you combine. They are different ways of arranging your Medicare coverage.

There is no universal choice that works the same way for every beneficiary. The useful comparison is how each structure handles the doctors you use, the prescriptions you take, monthly premiums, cost-sharing, and the way you prefer to receive care.

For a broader look at the major Medicare paths, see Understanding Your Medicare Coverage Options.

Can You Use Any Doctor With Medigap?

Generally, Medigap does not have a provider network like many Medicare Advantage plans.

You can generally see any doctor or hospital that accepts Medicare and is willing to treat Medicare patients. Because Original Medicare remains your primary coverage, your provider bills Medicare first.

This can be an important consideration for someone who sees specialists in different locations or wants broad access to Medicare-participating providers.

There are exceptions and details worth checking, including Medicare SELECT policies, which can have network requirements in exchange for certain cost arrangements.

What About Prescription Drugs?

Medigap policies sold since 2005 do not include prescription drug coverage.

If you have Original Medicare and Medigap and want Medicare prescription drug coverage, you generally need a separate Part D plan.

Part D plans have their own formularies, pharmacy networks, premiums, deductibles, copayments, and coinsurance. That means your prescription list should be part of the coverage review.

Before choosing a Part D plan, check the medications you take and the pharmacy you prefer rather than looking only at the plan premium.

Can You Change Medigap Plans Later?

Changing a Medigap policy is not always as simple as changing a Medicare Advantage or Part D plan during annual enrollment.

In most cases, federal law does not give you an automatic right to switch Medigap policies whenever you want. Outside your Medigap Open Enrollment Period, you may need to meet medical underwriting requirements unless you have a guaranteed issue right or another applicable protection. State rules can provide additional opportunities.

That is why the first purchase deserves careful attention. Do not assume that you can simply switch to another Medigap letter later without additional questions about your health or eligibility.

What Should You Check Before Buying a Medigap Policy?

Before you purchase, look at more than the monthly premium:

• Compare the Same Letter Across Companies: If you are interested in Plan G, compare Plan G with Plan G. Because benefits are standardized by letter in most states, this makes it easier to see how premiums differ between insurers.
• Check the Pricing Method: Find out whether the policy is community-rated, issue-age-rated, or attained-age-rated. The starting premium does not tell you how the price may change over time.
• Confirm Your Enrollment Rights: Find out whether you are inside your six-month Medigap Open Enrollment Period or have a guaranteed issue right.
• Review Part D Separately: Medigap does not include prescription drug coverage, so factor Part D into the overall coverage picture.
• Check Your State's Rules: Medigap policies are standardized differently in Massachusetts, Minnesota, and Wisconsin, and state law may provide additional enrollment protections elsewhere.
• Look at Long-Term Costs: Ask how the premium is determined and what factors could cause it to increase. The lowest starting premium is not necessarily the only cost detail worth examining.

A Simple Medigap Checklist

Before choosing a Medigap policy, gather your essential information:

Then review the policy benefits and premium structure before completing an application.

How Clarity65 Can Help With Medicare Supplement Options

Choosing Medicare coverage can feel complicated when several decisions happen at the same time.

Clarity65 works with independent licensed agents who can explain Medicare Supplement options, discuss the differences between Medigap and Medicare Advantage, and review available coverage based on factors such as location, doctors, prescriptions, and costs. Clarity65 states that its service is free to consumers and that it represents multiple Medicare carriers.

Clarity65 also provides annual plan reviews, helping consumers revisit their coverage as their circumstances and available options change.

You can learn more in the Clarity65 Medicare Supplement guide or start with the New to Medicare guide.

Final Thoughts

Understanding Medicare Supplement plans starts with one basic idea: Medigap works alongside Original Medicare rather than replacing it.

The lettered plans are standardized in most states, but premiums can vary between insurance companies. Medigap can help pay certain Original Medicare cost-sharing, but it does not generally cover prescription drugs, routine dental care, vision care, hearing aids, or long-term care.

Timing also matters. The six-month Medigap Open Enrollment Period is a one-time opportunity that starts when you are 65 or older and your Part B begins. After that window, buying or changing a policy can involve medical underwriting unless a guaranteed issue right or other protection applies.

Before choosing a policy, look at the plan letter, premium, pricing method, enrollment rights, Part D needs, and how the coverage fits with the way you expect to use healthcare.

The goal is to understand the coverage before you enroll, not simply choose a policy because its monthly premium looks attractive.

Frequently Asked Questions

Raul Gonzalez

Licensed Agent

Independent licensed Medicare advisor dedicated to plain-English guidance and personalized plan comparisons across leading national carriers.

Clarity65 is not connected with or endorsed by the U.S. government or the federal Medicare program.