Medigap Plans Explained: What They Are and How They Work with Medicare

When you first look at Medicare, it can feel like there are a lot of moving parts—and a lot of potential bills. Medigap plans, also called Medicare Supplement Insurance, are designed to help with that.

This guide walks through what Medigap plans are, how they work with Original Medicare, what they cover (and don’t cover), and how to decide if a Medicare Supplement plan might fit your situation.

What Is a Medigap Plan?

A Medigap plan is a private health insurance policy that helps pay some of the out-of-pocket costs that Original Medicare (Part A and Part B) does not fully cover.

These costs can include:

• Medicare Part A coinsurance and hospital costs
• Medicare Part B coinsurance or copayments
• Blood (first 3 pints)
• Hospice coinsurance or copayments
• Skilled nursing facility coinsurance
• Part A deductible
• In some plans, the Part B deductible (for older plans)
• Foreign travel emergency care (up to plan limits)

In short, Medigap helps “fill the gaps” in Original Medicare, which is where the name comes from.

How Medigap Works with Original Medicare

To understand Medigap, it helps to see how it fits into the bigger Medicare picture.

You must have Original Medicare

To buy a Medigap policy, you need to be enrolled in:

• Medicare Part A (hospital insurance), and
• Medicare Part B (medical insurance)

Medigap plans are add-ons, not stand-alone coverage. They work alongside Original Medicare—not instead of it.

Who pays what?

Here’s the basic flow when you have a Medigap plan:

1. You see a doctor or use a service that accepts Medicare.
2. Medicare pays its share of the approved amount.
3. Your Medigap plan pays its share of the remaining costs, based on the specific plan you have.
4. You may owe any remaining amount (if any), such as a deductible, copay, or coinsurance not covered by your Medigap policy.

Medigap plans generally do not use networks. If a provider accepts Medicare, they usually accept Medigap for covered services.

Medigap vs. Other Types of Medicare Coverage

Many people compare Medigap to other Medicare options and get confused. Here’s a clear breakdown.

Medigap vs. Medicare Advantage (Part C)

Medigap is not the same as Medicare Advantage.

• Medigap (Medicare Supplement)

  • Works with Original Medicare
  • Helps pay deductibles, coinsurance, and copays
  • Typically no provider network (you can see any provider that accepts Medicare)
  • Does not include prescription drug coverage (you usually add a separate Part D plan)

• Medicare Advantage (Part C)

  • An alternative way to receive Medicare benefits
  • Combines Part A and Part B, and often Part D, into one plan
  • Usually uses networks (HMO, PPO, etc.)
  • May include extra benefits not covered by Original Medicare, depending on the plan

You cannot have a Medigap plan and a Medicare Advantage plan at the same time.

Medigap vs. Medicare Part D (Drug Plans)

• Medigap: Helps pay medical costs that Original Medicare doesn’t fully cover
• Part D: Covers prescription drugs

If you want both supplemental coverage and drug coverage with Original Medicare, people commonly pair:

• Original Medicare (Part A and B)
• Medigap plan
• Medicare Part D prescription drug plan

Standardized Medigap Plans: What the Letters Mean

Medigap plans are identified by letters: Plan A, B, C, D, F, G, K, L, M, and N, plus some “high-deductible” versions in certain cases.

Same letter = same core benefits

One important feature:

A Medigap Plan G offers the same basic benefits no matter which company sells it.

Only the price and some extra features may differ between insurance companies, but the core coverage for a given plan letter is standardized.

Common Medigap plans and what they typically cover

Below is a simplified view of how some popular Medigap plans compare on major benefit categories. “Yes” means the plan usually covers 100% of that specific cost (after Medicare pays its share); “Partial” indicates a percentage.

*Plan N usually has copays for some office visits and emergency room visits instead of covering every dollar of Part B coinsurance.

Specific rules can vary and may change over time, so it’s wise to review the latest official Medigap benefits descriptions before choosing a plan.

What Medigap Plans Typically Cover

While coverage varies by plan letter, Medigap policies are mainly designed to help with:

• Hospital costs under Part A
  Extra days in the hospital after Medicare coverage is used, up to certain limits.

• Part A deductible
  Many plans pay some or all of the hospital deductible.

• Part B coinsurance or copayments
  Helps with the typical 20% you pay under Part B for doctor visits, outpatient care, and other services after the Part B deductible.

• Skilled nursing facility coinsurance
  Some plans help with the daily coinsurance for skilled nursing facility care after a certain number of days.

• Hospice care coinsurance/value
  Helps with copayments or coinsurance for hospice care under Part A.

• Emergency care while traveling abroad
  Several Medigap plans offer limited coverage for medical emergencies outside the United States, up to plan limits.

What Medigap Plans Do NOT Cover

Medigap is focused on Medicare cost-sharing, not on adding broad new types of benefits. In general, Medigap policies do not cover:

• Routine dental, vision, or hearing services
• Long-term care (custodial care in a nursing home or assisted living)
• Private-duty nursing
• Most prescription drugs (for that, people usually use a separate Part D plan)
• Care that Medicare itself doesn’t cover

If Original Medicare doesn’t approve or cover a service, your Medigap plan typically won’t pay for it either.

Who Might Consider a Medigap Plan?

People often look at Medigap when they:

• Prefer predictable out-of-pocket costs rather than variable bills
• Want the freedom to see any provider who accepts Medicare, often nationwide
• Travel frequently within the United States or, in some cases, internationally
• Expect frequent use of medical services and are concerned about coinsurance adding up
• Prefer to keep Original Medicare instead of joining a Medicare Advantage network

On the other hand, Medigap may be less appealing to those who:

• Are comfortable using a network-based plan like an HMO or PPO
• Want extra non-Medicare benefits commonly bundled into some Medicare Advantage plans
• Prefer lower monthly premiums even if that means more cost-sharing when they get care

When Can You Enroll in a Medigap Plan?

Timing matters with Medigap. Enrollment rules can affect whether you can get a policy and how much you pay.

Medigap Open Enrollment Period

Your Medigap Open Enrollment Period is a one-time window:

• It starts the first month you are both 65 or older and enrolled in Part B
• It lasts for 6 months

During this time:

• You usually have a “guaranteed issue” right to buy any Medigap plan sold in your state that’s available to you.
• Insurance companies generally cannot deny you coverage or charge more based on health conditions during this period.

This is often considered the most flexible and protected time to choose a Medigap plan.

After the open enrollment period

After this 6‑month window:

• In many situations, companies may use medical underwriting
• This means they can review your health, possibly charge higher premiums, limit coverage, or even decline your application in some cases

There are certain special situations (often called guaranteed issue rights) when you may still have a protected right to buy a Medigap plan without underwriting, such as losing other qualifying coverage. The exact rules can vary by state and situation.

Understanding Medigap Premiums

Medigap plans charge a monthly premium in addition to:

• Your Medicare Part B premium, and
• Any Part D drug plan premium, if you have one

How Medigap premiums are typically set

Companies commonly use one of three methods to set premiums:

1. Community-rated

   • Everyone pays the same premium regardless of age (within the same area and plan).

2. Issue-age-rated

   • Your premium is based on the age when you first buy the policy.
   • Premiums may increase over time for reasons like inflation, but not because you get older.

3. Attained-age-rated

   • Your premium is based on your current age and typically increases as you age, in addition to other possible increases.

Premiums can also differ based on:

• Where you live
• Which company you choose
• Whether you use any household or other available discounts
• Tobacco use, in some cases

Pros and Cons of Medigap Plans

To decide whether Medigap is worth exploring, it helps to see the tradeoffs clearly.

Potential advantages

• Lower and more predictable cost-sharing
  Helps protect against high out-of-pocket costs for covered services under Original Medicare.

• Freedom to choose providers
  Typically, you can see any health provider or visit any facility that accepts Medicare, often with no referrals.

• Standardized benefits
  Plan letters are standardized, which can simplify comparing coverage.

• Useful for frequent travelers
  For people who move or travel often within the U.S., this flexibility can be valuable. Some plans also offer limited foreign emergency coverage.

Potential drawbacks

• Additional monthly premium
  You pay a Medigap premium on top of your Part B and (usually) Part D premiums.

• No built-in prescription drug coverage
  You generally need to add a separate Part D plan for medications.

• Limited to Medicare-covered services
  Medigap doesn’t usually add benefits beyond what Medicare covers; it mostly helps with cost-sharing.

• Enrollment limitations after the first window
  After your Medigap Open Enrollment Period, it may be harder or more expensive to get some plans, depending on your health and your state’s rules.

Key Questions to Ask Before Choosing a Medigap Plan

If you’re considering Medigap, it can help to reflect on a few practical questions:

1. How often do I use medical services now, and what might I expect in the future?
2. Do I value broad provider choice, or am I comfortable with a network?
3. What’s my budget for monthly premiums vs. potential out-of-pocket costs?
4. Do I plan to travel frequently, within or outside the U.S.?
5. Am I in my Medigap Open Enrollment Period, or have I already passed that window?
6. How important is it to keep my coverage structure simple and predictable?

Writing down your answers can make it easier to compare Medigap with other Medicare options.

Quick Medigap Summary 📝

Medigap plans:

• Are Medicare Supplement policies sold by private insurers
• Work with Original Medicare (Part A and B), not instead of it
• Help pay deductibles, coinsurance, and copays that Medicare doesn’t fully cover
• Are standardized by letter (Plan A, G, N, etc.), so benefits are similar across companies for the same letter
• Do not include prescription drug coverage, dental, vision, or long-term care
• Are usually easiest to get and most flexible during your 6‑month Medigap Open Enrollment Period

Final Thoughts

Medigap plans exist to help people with Original Medicare manage out-of-pocket costs and maintain flexibility in choosing providers. Understanding what Medigap is, what it covers, and how it fits into the overall Medicare landscape can make your choices clearer and more confident.

If you decide to look into Medigap further, it can be useful to:

• Review your current and expected healthcare needs
• Compare the standardized benefit charts for different plan letters
• Examine premiums and features from several insurers in your area
• Consider how Medigap would fit with your Part D and other coverage choices

Once you have that full picture, you’ll be in a stronger position to decide whether a Medigap plan aligns with your health needs, budget, and preferences for how you receive care.