Medicare Supplement Insurance

What Is Medigap —
and Do You Need It?

Q: Can I have Medigap and Medicare Advantage at the same time?

No — you cannot have both. Medigap works only alongside Original Medicare (Parts A and B). If you're enrolled in Medicare Advantage, you are not using Original Medicare as your primary coverage, so a Medigap policy cannot legally be used to pay your costs. If you want to switch from Medicare Advantage to Original Medicare + Medigap, you can do so during enrollment periods — but you will likely face medical underwriting for the Medigap policy unless you have guaranteed issue rights.

Q: Does Medigap cover prescription drugs?

No. Medigap plans do not include prescription drug coverage. If you have Original Medicare + Medigap, you need to add a standalone Medicare Part D plan for prescription coverage, which is an additional monthly premium. The upside is you can choose the Part D plan that best fits your specific medications independently of your Medigap plan.

Q: Is Medigap more expensive than Medicare Advantage?

Monthly, generally yes. A Medigap + Part D combination typically adds more to your Part B premium than a Medicare Advantage plan's added premium does. However, the monthly comparison isn't the full picture. With Medigap, your total annual costs are close to fixed. With Medicare Advantage, you pay less monthly but accumulate cost-sharing each time you use care, up to an annual cap. In a year with significant health needs, Medigap can end up costing about the same or less in total.

Original Medicare is excellent coverage — but it leaves gaps in how much you could end up paying out of pocket in a serious year. A serious illness, major surgery, or extended hospital stay can add up quickly with no built-in ceiling. Medigap plans are built to fill those gaps. Here's everything you need to know to decide if one is right for you.

📅 Reviewed and updated for 2026

The Basics

What Is Medigap?

Medicare Supplement Insurance — called Medigap — is sold by private insurance companies to fill the "gaps" in Original Medicare coverage. It helps pay some of the costs that Original Medicare doesn't cover on its own.

When you have a medical service under Original Medicare, Medicare pays its approved share of the cost. The remaining share is yours — with no built-in cap. That might be manageable in a routine year, but a serious illness, surgery, or hospitalization can change that quickly.

A Medigap plan kicks in after Medicare pays its share and covers most or all of what's left, depending on which plan you choose. You pay a monthly premium to the private insurer, and in exchange, your potential out-of-pocket exposure drops significantly for covered services.

Medigap plans are standardized by the federal government. Plan G from Company A covers exactly the same benefits as Plan G from Company B — the difference between insurers comes down to premium and service reputation, not what's covered. This makes comparison shopping straightforward.

It's important to understand: Medigap works only alongside Original Medicare (Parts A and B). It does not work with Medicare Advantage. If you choose Medicare Advantage, you cannot also have a Medigap policy.

How the cost-sharing generally splits

Hospital stay (Part A) Medicare pays

Part A deductible Medigap covers, depending on plan

Doctor visit (Part B) Medicare pays its share

Your remaining coinsurance Medigap covers, depending on plan

Part B deductible You pay, on most plans

Prescription drugs Not covered — need Part D

Exactly which items Medigap covers depends on which lettered plan you choose. A PharmSurance advisor can walk you through the specifics.

Plan Options

The Most Common Medigap Plans

Medigap plans are labeled by letter (A through N) — 10 in total. CMS standardizes what each letter covers, so a Plan G is the same everywhere, no matter which company sells it. Plans G and N are the ones most commonly chosen by new enrollees today, so we've detailed those above — but every plan is listed below with what it actually covers, including the two that are closed to new enrollees.

Your Open Enrollment Window Opens

The month you turn 65 and are enrolled in Medicare Part B, your 6-month Medigap Open Enrollment Period begins. This is a federally guaranteed right. During this window, no insurer can deny you a Medigap policy or charge you more based on your health history.

You Choose Any Plan From Any Insurer

During the 6-month window, you have guaranteed issue rights. You can choose any Medigap plan available in your state from any insurer, regardless of pre-existing conditions, medical history, or health status. The insurer must accept you at their standard rate.

The Window Closes

Six months after your Part B start date, the open enrollment window closes permanently. There is no way to reopen it based on age alone.

After the Window: Medical Underwriting

Once the window closes, insurers in most states can use medical underwriting — meaning they can review your health history, charge you significantly more, or outright deny you coverage based on pre-existing conditions. Some states have additional protections; most do not. This is the risk of waiting.

What This Means in Practice

The Window Is a One-Time Opportunity

A 65-year-old in excellent health has the same guaranteed access to Medigap as a 65-year-old with diabetes, heart disease, and a history of cancer — during the open enrollment window. That equality disappears the moment the window closes.

This is why timing your Medicare enrollment correctly matters so much. If you delay Part B enrollment because you're still working, your Medigap window doesn't start until you do enroll — which can work in your favor if you plan ahead.

A PharmSurance advisor will map out your specific timeline and make sure you don't accidentally let this window pass during the Medicare transition.

Note: A small number of states (CT, MA, NY) have additional guaranteed issue protections beyond the federal rules. Ask us if you live in one of these states.

Full Comparison

Medigap vs. Medicare Advantage
vs. Original Medicare Alone

Three different approaches to Medicare coverage. Each has real advantages and real trade-offs. Here's how they compare across the factors that matter most.

← Scroll to compare all three options →

Factor	🛡️ Original Medicare + Medigap + Part D	📦 Medicare Advantage (Part C)	⚕️ Original Medicare Alone
Doctor choice	● Any Medicare-accepting doctor in the U.S. — no networks	● Generally requires using the plan's provider network	● Any Medicare-accepting doctor — no networks
Out-of-pocket cap	● No federal cap, but Medigap is designed to limit your exposure for covered services	● Required to have a yearly cap on in-network costs	● No cap — your share continues without a ceiling
Drug coverage	● Not included — add a standalone Part D plan	● Usually included in the plan	● Not included — add a standalone Part D plan
Travel / nationwide use	● Nationwide — works anywhere in the U.S.	● Generally tied to your local network	● Nationwide
Prior authorization	● Rarely required for Medicare-covered services	● Commonly required for certain services	● Rarely required
Plan stability	● Coverage structure is generally consistent year to year once enrolled	● Plan terms are renegotiated and can change each January	● Coverage structure is generally consistent year to year

Honest Assessment

The Real Pros and
Cons of Medigap

Medigap isn't right for everyone. Here's a straight assessment of what it does well and where it falls short.

✅ The Advantages

✓Predictable costs. You pay your monthly premium — and very little else for covered services. No surprise bills, no coinsurance stacking up after a hospitalization.

✓Any doctor, anywhere. No provider networks. No referrals. If a doctor or hospital accepts Medicare, they accept you — in any state.

✓No prior authorization. Medigap follows Medicare's coverage decisions — and Medicare rarely requires prior authorization for covered services.

✓Stability. Once you're enrolled, your benefits don't change year to year. No annual plan review anxiety.

✓Great for travelers. Works in all 50 states. Some plans include foreign travel emergency coverage.

✓Ideal for complex health needs. If you see multiple specialists or have chronic conditions, the freedom and predictability of Medigap is often worth the higher premium.

⚠️ The Trade-Offs

—Higher monthly cost. Medigap + Part D adds to your Part B premium. In healthy years with minimal care use, the total may be more than a Medicare Advantage plan.

—No drug coverage. You must add a standalone Part D plan — an additional premium and coverage to manage.

—Narrower coverage focus. Medigap covers Medicare's cost-sharing — it doesn't layer on additional coverage the way some Medicare Advantage plans structure themselves. Worth understanding what each approach does and doesn't include.

—Premiums increase with age. Most Medigap policies use attained-age or issue-age pricing, meaning your premium may increase over time as you age.

—Hard to switch later. After the open enrollment window, switching plans or insurers typically requires medical underwriting in most states.

—Not the right fit for everyone. If you're healthy, rarely use medical care, or have a tight budget — Medicare Advantage may be worth discussing as an alternative.

Who It's Best For

Is Medigap Right for You?

No plan fits everyone. Here are the situations where Medigap tends to be the stronger choice.

✈️

Frequent Travelers

If you travel often — especially out of state or internationally — Medigap's nationwide coverage and no-network design is a significant advantage. Medicare Advantage plans are largely local.

🏥

Complex or Chronic Conditions

Multiple specialists, frequent hospital visits, or chronic conditions that require ongoing care can accumulate significant coinsurance under Original Medicare alone. Medigap eliminates most of that exposure.

🩺

Strong Doctor Relationships

If you have trusted physicians — specialists, surgeons, or a primary care doctor you've been with for years — Medigap lets you keep seeing them without worrying about network status.

📊

People Who Value Predictability

A fixed monthly premium with near-zero additional out-of-pocket costs makes budgeting in retirement simple. If you dislike financial surprises, Medigap offers unmatched cost predictability.

🛡️

Those Who Want Stability

Medigap benefits don't change year to year. No annual plan shopping, no benefit cuts, no network changes in January. Once you're in, you're in.

🔬

People Who Want Provider Freedom

No referrals required. No gatekeeping. If you want the ability to see any specialist or seek a second opinion without navigating network rules, Medigap provides that freedom.

Common Questions

Frequently Asked
Medigap Questions

Can I have Medigap and Medicare Advantage at the same time?

No — you cannot have both. Medigap works only alongside Original Medicare (Parts A and B). If you're enrolled in Medicare Advantage, you are not using Original Medicare as your primary coverage, so a Medigap policy cannot legally be used to pay your costs. If you want to switch from Medicare Advantage to Original Medicare + Medigap, you can do so during enrollment periods — but you will likely face medical underwriting for the Medigap policy unless you have guaranteed issue rights.

Does Medigap cover prescription drugs?

No. Medigap plans do not include prescription drug coverage. If you have Original Medicare + Medigap, you need to add a standalone Medicare Part D plan for prescription coverage. This is an additional monthly premium. The upside is you can choose the Part D plan that best fits your specific medications independently of your Medigap plan.

What's the difference between Plan G and Plan N — which should I choose?

Plan G is the most comprehensive plan available to new enrollees — after your annual Part B deductible, you pay very little for covered Medicare services. Plan N generally has a lower monthly premium but includes small copays for office and ER visits, and doesn't cover Part B excess charges. Whether N or G comes out ahead for you depends on how often you use care — a PharmSurance advisor can walk through the math for your specific situation. For most people who rarely see doctors, Plan N tends to come out ahead on cost. For people with frequent medical needs, Plan G's predictability tends to win.

Can I be denied a Medigap plan because of a pre-existing condition?

During your 6-month open enrollment window — which starts the month you turn 65 and enroll in Part B — no insurer can deny you or charge you more based on health history. After that window closes, most states allow medical underwriting, meaning insurers can decline you or charge significantly higher premiums based on pre-existing conditions. A handful of states (Connecticut, Massachusetts, New York, and a few others) have stronger protections. This is why enrolling during your window is so critical.

Is Medigap more expensive than Medicare Advantage?

Monthly, generally yes. A Medigap + Part D combination typically adds more to your Part B premium than a Medicare Advantage plan's added premium does. However, the monthly comparison isn't the full picture. With Medigap, your total annual costs are close to fixed — you pay your premium and very little else. With Medicare Advantage, you pay less monthly but accumulate cost-sharing each time you use care, up to an annual cap. In a year with significant health needs, Medigap can end up costing about the same or less in total. The right answer depends on your health, your usage patterns, and how you weigh monthly certainty against potential future costs — worth walking through with an advisor rather than assuming.

Can I switch from Medicare Advantage to Medigap later?

You can switch from Medicare Advantage to Original Medicare during the annual Medicare Advantage Open Enrollment Period (January 1–March 31) or the Annual Enrollment Period (October 15–December 7). However, once you switch back to Original Medicare, getting a Medigap plan will likely require medical underwriting — meaning you could be denied or charged more based on your health at that point. The exception: you have guaranteed issue rights for Medigap if your Medicare Advantage plan is leaving your service area or goes bankrupt. This asymmetry is one reason why the original Medigap enrollment decision is so important to get right the first time.

Do Medigap plans vary by insurance company?

The benefits of each lettered plan are standardized and identical across all insurers — a Plan G from Aetna covers exactly the same services as a Plan G from Mutual of Omaha. What varies is the monthly premium, the insurer's financial strength, their reputation for customer service, and how they structure premium increases over time. Some companies use "community rating" (everyone pays the same price regardless of age), "issue-age rating" (price based on your age when you bought the policy), or "attained-age rating" (price increases as you age). Understanding pricing methodology matters for long-term cost planning. A PharmSurance advisor will help you compare options available in your state.

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Official Government Resource

Want to Review the Full Picture First?

The official Medicare & You handbook, published annually by CMS, covers every part of Medicare in plain language — enrollment rules, plan types, and your rights as a beneficiary. Free to read, no account needed.

Read the Medicare & You Handbook →

When you're ready, a PharmSurance advisor will analyze your individual situation and help you understand your options clearly — something a general handbook can't do.

Not Sure Which Path
Is Right for You?

Medigap vs. Medicare Advantage is the most important Medicare decision you'll make — and the right answer depends on your doctors, medications, budget, and health. A PharmSurance advisor will walk through all of it with you, at no cost.

Talk to an Advisor →

Your premium is the same whether you enroll through us or go directly to a carrier — what you get with PharmSurance is a personalized comparison across multiple carriers, not just one company's plans.

We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. If you submit your information on this site, it will be provided to one or more licensed insurance agents, who may call, email, or text you about Medicare Advantage, Medicare Supplement, and Prescription Drug Plan options.

What Is Medigap —and Do You Need It?