When people first enroll in Medicare, they quickly realize that Parts A and B, also called Original Medicare, don’t cover everything. Yes, they handle hospital and medical costs — but there are gaps that can lead to unexpected bills.
You’re still responsible for deductibles, copayments, and coinsurance, and there’s no out-of-pocket maximum. That means a serious illness or long hospital stay could become very expensive.
That’s where Medicare Supplement Insurance, also known as Medigap, comes in. It’s private insurance that helps cover the costs Original Medicare doesn’t pay — filling those “gaps” in coverage and giving you greater financial protection and peace of mind.
What Is Medicare Supplement (Medigap)?
Medicare Supplement Insurance is designed to work alongside Original Medicare. It’s sold by private insurance companies, but it’s regulated by both federal and state laws to protect consumers.
When you have Medigap, Medicare pays its share of the approved amount for covered services, and then your Medigap plan pays its share. This can dramatically reduce or even eliminate what you owe out of pocket.
Think of it this way:
- Medicare Part A covers hospital care.
- Medicare Part B covers doctor visits and outpatient care.
- Medigap covers what’s left over — your share of the bill.
It doesn’t replace Medicare; it supplements it.
Why Medigap Exists
Before Medigap plans were standardized, insurance companies sold many different versions of “Medicare supplements,” often confusing people with inconsistent benefits. In 1992, the government stepped in and standardized the plans, ensuring fairness and transparency.
Today, no matter which company you buy from, the benefits for each plan letter are exactly the same. A Plan G from one company offers identical coverage to a Plan G from another — the only difference is price and service.
This standardization means you can confidently shop around, knowing you’re comparing apples to apples.
Who Can Get a Medigap Plan
To buy a Medigap policy, you must:
- Be enrolled in Medicare Parts A and B
- Live in the state where the plan is offered
- Not be enrolled in a Medicare Advantage plan (you can’t have both at the same time)
The best time to sign up is during your Medigap Open Enrollment Period — the six months that start when you’re 65 or older and enrolled in Part B.
During this time, you can buy any plan offered in your state without medical underwriting.
That means:
✅ No health questions
✅ No higher premiums for pre-existing conditions
✅ Guaranteed acceptance
After this window closes, you can still apply, but insurance companies may review your medical history and decide whether to accept you or charge a higher rate.
How Medigap Works
Here’s how the process looks in everyday terms:
- You go to the doctor or hospital.
- Medicare pays its portion of the approved charges.
- Your Medigap plan pays the rest (depending on the plan you have).
You’ll rarely need to deal with separate bills. Most providers bill Medicare directly, and the claim is automatically forwarded to your Medigap insurer.
The result? Predictable costs, simpler paperwork, and fewer surprises.
What Medigap Covers
All Medigap plans cover some or all of the following expenses:
- Part A coinsurance and hospital costs up to an extra 365 days after Medicare benefits are used up
- Part B coinsurance or copayments
- First three pints of blood (Medicare doesn’t cover these)
- Part A hospice care coinsurance or copayments
- Skilled nursing facility coinsurance (for some plan types)
- Part A deductible (for hospital stays)
- Part B deductible (only in older plans C and F)
- Part B excess charges (if a doctor charges more than Medicare’s approved amount)
- Foreign travel emergency care (up to plan limits)
Not every plan covers all of these, but even the most basic ones protect you from the largest and most common expenses.
Standardized Plans: A–N
There are currently 10 standardized Medigap plans available in most states, identified by letters: A, B, C, D, F, G, K, L, M, N.
Each letter represents a specific set of benefits. For example:
- Plan A is the most basic, covering core benefits like hospital coinsurance and hospice care.
- Plan F was historically the most comprehensive, covering almost everything, but it’s no longer available to people new to Medicare after 2020.
- Plan G has become the most popular replacement for F — it covers nearly everything except the Part B deductible.
- Plan N offers slightly lower premiums but requires small copayments for doctor or ER visits.
- Plans K and L have lower monthly premiums but higher cost-sharing, plus an annual out-of-pocket limit.
In Massachusetts, Minnesota, and Wisconsin, plans are standardized differently, but the principle is the same: each plan level offers a fixed package of benefits.
Popular Plans and How They Differ
Plan G – The All-Around Favorite
Plan G covers everything that Plan F did except for the small Part B deductible. For many people, that’s an easy trade-off, because premiums for Plan G are often lower than what they would have paid for Plan F. It’s widely considered the best value among Medigap plans today.
Plan N – Affordable and Practical
Plan N keeps premiums even lower by asking you to pay small copays — up to $20 for office visits and $50 for ER visits that don’t result in hospital admission. It doesn’t cover Part B excess charges, but for many people who see doctors who accept Medicare assignment, this isn’t an issue.
Plans K and L – Lower Premium, Higher Sharing
If you prefer lower monthly premiums and are comfortable sharing some costs, these plans might fit you. They cover a percentage (50 % or 75 %) of certain expenses and include a yearly out-of-pocket maximum. Once you reach that limit, the plan covers 100 % for the rest of the year.
What Medigap Doesn’t Cover
While Medigap fills many gaps, it doesn’t cover everything. Specifically, Medigap does not include:
- Prescription drug coverage (you’ll need Part D for that)
- Dental, vision, or hearing care
- Long-term or custodial care (help with bathing, dressing, etc.)
- Private-duty nursing or stays in assisted-living facilities
For those services, you can combine Medigap with standalone plans or other types of supplemental insurance.
Costs and Premiums
The cost of Medigap insurance varies based on:
- The plan letter (A through N)
- The insurance company
- Your age, location, and tobacco use
- Whether the plan uses attained-age, issue-age, or community-rated pricing
Premiums can range from about $80 to $250 per month, depending on where you live and which plan you choose.
Remember:
- You’ll still pay your Part B premium.
- Medigap premiums are in addition to that.
But in exchange, you get protection from unpredictable bills and the freedom to see any doctor in the U.S. who accepts Medicare.
Freedom to Choose Doctors and Hospitals
One of the biggest advantages of Medigap over Medicare Advantage is flexibility.
With Medigap, you can visit any doctor, specialist, or hospital in the United States that accepts Medicare — no networks, no referrals, no restrictions. This makes Medigap especially appealing to people who travel frequently or have multiple doctors in different states.
You can also use Medigap coverage when traveling outside the U.S., as certain plans pay up to 80 % of emergency medical costs abroad (after a small deductible and within plan limits).
Medigap vs. Medicare Advantage (Part C)
Many people compare Medigap and Medicare Advantage (Part C) when deciding how to manage their Medicare coverage.
Here’s the key difference:
| Feature | Medigap | Medicare Advantage |
|---|---|---|
| Type of coverage | Supplements Original Medicare | Replaces Original Medicare |
| Provider access | Any provider nationwide who accepts Medicare | Network-based (HMO/PPO) |
| Prescription coverage | No (requires Part D) | Often included |
| Out-of-pocket limit | None (but minimal leftover costs) | Annual limit (varies by plan) |
| Extras (vision, dental, etc.) | Usually not included | Often included |
| Travel flexibility | Nationwide | Usually local or regional |
| Premiums | Higher monthly, fewer surprises | Lower monthly, more cost sharing |
Neither option is universally “better” — it depends on your priorities.
If you value freedom and predictability, Medigap might be ideal.
If you prefer one-card convenience and extras, Medicare Advantage may suit you better.
How to Enroll
You can apply for a Medigap plan directly from any insurance company that offers them in your state.
Here’s a simple step-by-step outline:
- Enroll in Medicare Parts A and B.
- Compare Medigap plans available in your ZIP code.
- Apply during your Open Enrollment Period for guaranteed acceptance.
- Pay your first premium — and your coverage can start immediately.
If you apply outside your open-enrollment window, the insurer may review your health history. But if you’re switching from another Medigap plan or moving to a new state, you may qualify for special rights that make changing plans easier.
How to Choose the Right Plan
Choosing a Medigap plan doesn’t have to be overwhelming. Here’s a simple way to think about it:
- Plan G: For people who want full protection and minimal out-of-pocket costs.
- Plan N: For those who prefer lower monthly premiums and don’t mind small copays.
- Plan K or L: For budget-minded individuals who are okay with sharing more costs up front.
When comparing plans:
- Check if your doctor accepts Medicare (almost all do).
- Review your budget and expected medical needs.
- Get quotes from a few insurers — same coverage, different prices.
You can compare standardized Medigap plans easily on medicare.gov or on your state’s official Medicare site.
Keeping Your Medigap Plan
Once you have a Medigap policy and pay your premiums on time, it automatically renews every year. You don’t need to re-apply, even if your health changes.
However, premiums may increase over time, either because of your age or general cost adjustments by the company. If that happens, you can compare other insurers and switch plans, though you may need to answer some health questions if you’re outside your open-enrollment period.
Common Questions About Medigap
Do I still need Part B if I have Medigap?
Yes. Medigap only works with Original Medicare — you must have Parts A and B active.
Can I have Medigap and Medicare Advantage at the same time?
No. You can only have one or the other.
Does Medigap cover my spouse too?
No. Each person must have their own separate Medigap policy.
Can I switch plans later?
Yes, but acceptance isn’t guaranteed outside open enrollment, unless you qualify for a special situation (for example, your plan leaves the area or you move to another state).
Key Takeaways
Medicare Supplement (Medigap) plans exist to give you financial protection and freedom that Original Medicare alone doesn’t provide.
Here’s what to remember:
- Medigap fills the gaps left by Parts A and B.
- Plans are standardized by letter (A–N).
- Coverage is identical from one insurer to another — only price and service differ.
- You can see any doctor or hospital in the U.S. that accepts Medicare.
- The best time to buy is during your six-month Medigap Open Enrollment Period.
Medigap isn’t flashy — it doesn’t include dental or gym memberships — but it provides something even more valuable: predictability. You’ll know what you owe, where you can go, and that your coverage travels with you anywhere in the country.
At GetMedicareSolutions, we believe that understanding Medicare shouldn’t require a dictionary. Medigap is simply a way to make your Medicare stronger — helping you plan for the future with fewer surprises and more confidence.
Want to compare plans side by side?
Check out our upcoming Medicare Supplement Comparison Chart to see exactly how each plan (A through N) stacks up — clear, simple, and easy to read.