If you’re approaching retirement or already enrolled in Medicare, you may have heard the term Medicare supplement insurance — but understanding exactly what it does can feel overwhelming. The good news is that once you break it down, it’s much more manageable than it seems. And knowing how it works could make a real difference in protecting your financial security down the road.

Here’s something that surprises many retirees: Original Medicare doesn’t cover everything. While Medicare Parts A and B provide essential health coverage, they also leave some notable gaps. For example, Part B typically requires you to pay 20% of the cost for outpatient services — and that percentage has no annual cap. Hospital deductibles add another layer of expense, and without an out-of-pocket maximum, a serious illness or extended hospital stay could result in bills that quickly add up. For retirees living on a fixed income, those unexpected costs can put real pressure on savings that took decades to build.

That’s where Medicare supplement insurance, also known as Medigap, comes in. These private insurance plans are specifically designed to help cover some of the costs that Original Medicare leaves behind — things like coinsurance, copayments, and deductibles.

In this article, we’ll walk you through what Medigap plans actually cover, how they’re structured, and what to consider when deciding if one might be right for your situation. Think of it as a straightforward guide to help you make a more informed decision about your healthcare coverage in retirement.

What Is Medicare Supplement Insurance (Medigap)?

Medicare supplement insurance — also called Medigap — is private health insurance designed to work alongside Original Medicare. When you receive care, Original Medicare (Parts A and B) pays its share of approved costs, and your Medigap policy helps cover some or all of what’s left. That can include things like deductibles, copayments, and coinsurance that would otherwise come out of your pocket.

It’s important to understand what Medigap is not. It is not the same as Medicare Advantage (Part C). Medicare Advantage plans replace Original Medicare entirely, while Medigap works alongside Original Medicare — it does not replace it. If you have a Medicare Advantage plan, you generally cannot use a Medigap policy at the same time.

One of the most helpful things about Medigap is that the plans are federally standardized. The federal government defines what each plan must cover, and plans are labeled with letters — Plan A, Plan B, Plan C, Plan D, Plan F, Plan G, Plan K, Plan L, Plan M, and Plan N. No matter which private insurance company sells you Plan G, for example, the core benefits of that plan are the same. This makes it easier to compare your options without getting lost in confusing fine print.

That said, states do regulate certain aspects of how Medigap policies are sold and priced. Premiums can vary depending on the insurance company, the state you live in, and the pricing method the insurer uses — so it pays to compare carefully.

To purchase a Medigap policy, you must be enrolled in both Medicare Part A and Medicare Part B. Medigap policies only cover one person, so spouses each need their own separate policy.

What Gaps Does Original Medicare Leave Behind?

Original Medicare does a lot of good — but it doesn’t cover everything. In fact, it leaves several significant gaps that can add up to thousands of dollars in out-of-pocket costs, even for a routine health event. Understanding these gaps is the first step toward protecting your retirement budget.

The Costs Medicare Doesn’t Cover

• Part A Hospital Deductible: Before Medicare pays a dime for inpatient hospital care, you’re responsible for a deductible of approximately $1,676 per benefit period in 2024. Importantly, this isn’t an annual deductible — it resets each time a new benefit period begins.
• Part A Coinsurance for Extended Stays: If your hospital stay stretches beyond 60 days, you’ll owe $419 per day for days 61–90, and costs climb even higher after that.
• Part B Coinsurance: For outpatient care — doctor visits, lab work, physical therapy — you’re typically responsible for 20% of all Medicare-approved costs. There’s no annual cap on this amount, which means a serious illness could leave you exposed to unlimited costs.
• Skilled Nursing Facility Coinsurance: After day 20 in a skilled nursing facility, you owe $209.50 per day out of pocket.
• No Out-of-Pocket Maximum: Unlike many private insurance plans, Original Medicare has no yearly limit on what you can be asked to pay.

A Real-World Example: Meet Carol

Carol is a 68-year-old retiree who experiences a health scare and spends 10 days in the hospital, followed by several weeks of outpatient physical therapy. Under Original Medicare, here’s what she might face:

• Hospital stay: She owes the $1,676 Part A deductible right away.
• Physical therapy: Her approved therapy costs total $4,000. Medicare covers 80%, leaving Carol with $800 in Part B coinsurance.
• Total estimated out-of-pocket: roughly $2,476 — and that’s for a relatively straightforward recovery.

If Carol’s recovery had been longer or required a skilled nursing facility, those numbers could have grown significantly. This is exactly where Medicare supplement insurance — also called Medigap — can make a meaningful difference. It’s designed to help cover many of these leftover costs, giving you more financial predictability when you need care.

The Standardized Medigap Plans: A Through N

One of the most helpful things about Medicare supplement insurance is that the federal government standardizes the plans. That means every insurance company offering a Medigap plan must follow the same rules about what each plan covers. Currently, plans available to most new Medicare beneficiaries include Plans A, B, D, G, K, L, M, and N.

You may have heard of Plans C and F — and they do still exist, but with an important catch. Due to federal legislation known as MACRA, these plans are only available to people who became eligible for Medicare before January 1, 2020. Because Plans C and F covered the Part B deductible (known as “first-dollar coverage”), Congress phased them out for newer enrollees.

The Plans Most People Choose

While all the plans serve a purpose, three tend to rise to the top for new enrollees:

• Plan G is the most comprehensive option available to people new to Medicare. It covers the Part A deductible, Part A and Part B coinsurance, skilled nursing facility coinsurance, foreign travel emergencies, and more. The only cost you’re still responsible for is the annual Part B deductible — around $240 in 2024. For people who want maximum predictability in their healthcare costs, Plan G is often the top choice.
• Plan N offers a lower monthly premium than Plan G in exchange for a little more cost-sharing. You’ll pay up to a $20 copay for most doctor’s office visits and up to $50 for emergency room visits. Additionally, Plan N does not cover Part B excess charges, which can apply with certain providers who don’t accept Medicare assignment.
• Plans K and L are cost-sharing plans with lower premiums and built-in out-of-pocket maximums. They cover a percentage of costs rather than the full amount, making them worth considering for people who are generally healthy and comfortable with some financial exposure.

Why Standardization Works in Your Favor

Here’s the key takeaway: because these plans are standardized by law, Plan G from one insurance company provides exactly the same benefits as Plan G from another. The coverage is identical — the only real difference is the premium. That means you can shop confidently, knowing that finding a lower premium doesn’t mean settling for less coverage.

When Can You Enroll in a Medigap Plan?

Timing matters a great deal when it comes to signing up for a Medigap plan. Understanding your enrollment windows can mean the difference between getting the coverage you want at a standard rate — and facing higher costs or even being turned down altogether.

Your Medigap Open Enrollment Period

The most important window is your Medigap Open Enrollment Period. This six-month period begins on the first day of the month in which you are both age 65 or older and enrolled in Medicare Part B. During this window, insurance companies are required by federal law to sell you any Medigap plan they offer — at standard rates — regardless of any pre-existing health conditions. This protection is known as guaranteed issue, and it’s one of the most valuable rights you have as a new Medicare enrollee.

Once this six-month window closes, things can get more complicated. In most states, insurers are allowed to use medical underwriting to evaluate your health history. That means they may charge you higher premiums, exclude certain conditions from coverage, or deny your application entirely based on your health status.

Guaranteed-Issue Rights Outside Open Enrollment

Even outside your initial Open Enrollment Period, certain life events can trigger guaranteed-issue rights, giving you a protected opportunity to purchase a Medigap plan without going through medical underwriting. Common qualifying situations include:

• Losing employer-sponsored health coverage
• Your Medicare Advantage plan leaving your service area or stopping its Medicare contract
• Being enrolled in a Medicare SELECT plan that closes in your area

These rights are time-sensitive, so it’s important to act quickly if a qualifying event occurs. For broader context on Medicare enrollment timelines, visit our guide on Medicare open enrollment.

The Bottom Line

Your Medigap Open Enrollment Period is your best opportunity for guaranteed access to coverage. Enrolling during this window protects you from potential denials or higher costs down the road. Because everyone’s situation is different, we encourage you to speak with a licensed insurance advisor who can help you evaluate your specific options and timing.

How Much Does Medicare Supplement Insurance Cost?

One of the first questions people ask when exploring Medicare supplement insurance is, “What will I actually pay each month?” The honest answer is: it depends. But understanding what drives the cost can help you make a smarter decision for your budget and your health needs.

How Premiums Are Calculated

Insurance companies use three different methods to set Medigap premium prices, and knowing the difference matters:

• Community-rated: Everyone in the plan pays the same monthly premium, regardless of age. A 65-year-old and a 75-year-old pay the same amount. This approach can be especially valuable as you get older.
• Issue-age-rated: Your premium is based on how old you are when you first buy the policy. The younger you are when you enroll, the lower your starting rate — and that rate stays relatively stable over time, regardless of how old you get later.
• Attained-age-rated: Your premium starts out lower, which can look attractive at first glance — but it increases as you age. This is the most common pricing method, so it’s important to factor in potential future increases when comparing plans.

Other Factors That Affect Your Premium

Beyond the pricing method, several other factors influence what you’ll pay:

• Where you live: Premiums vary significantly by state and even by county.
• Tobacco use: Smokers typically pay higher premiums than non-smokers.
• Gender: Some states allow insurers to consider gender when setting rates.
• Plan type: A Plan G, Plan N, and Plan K all offer different levels of coverage — and different price points to match.

What to Expect in Terms of Cost

While we can’t quote specific carrier prices here, a Plan G policy might generally fall somewhere in the range of $100 to $300 per month, depending on your age, location, and the insurer. It’s a wide range, which is exactly why comparing options is so important.

It’s also worth remembering that Medigap premiums are separate from your Medicare Part B premium, which everyone enrolled in Medicare pays. So your total monthly cost will include both.

That said, for people who use healthcare services regularly, the predictability of Medigap coverage can be a genuine financial advantage. Knowing your costs are capped — rather than facing a surprise bill after a hospital stay — gives many people real peace of mind and can easily offset the monthly premium over time.

Medicare Supplement Insurance vs. Medicare Advantage: Key Differences

When you become eligible for Medicare, you’ll quickly discover there are two main paths for handling your healthcare costs beyond Original Medicare. Understanding how they differ can make a significant impact on your healthcare experience and your wallet.

Medicare Supplement Insurance (Medigap) works alongside Original Medicare — it doesn’t replace it. You keep your Medicare Parts A and B, and your Medigap plan steps in to help cover costs like deductibles, copayments, and coinsurance. One of the biggest advantages? You can visit any doctor, specialist, or hospital anywhere in the United States that accepts Medicare — no networks, no referrals, no hassle. This makes Medigap an especially strong fit for people managing complex or chronic health conditions, or for those who travel frequently and want consistent coverage wherever they go.

Medicare Advantage plans, on the other hand, work differently. Instead of supplementing Original Medicare, these plans replace it entirely through a private insurance company approved by Medicare. Most Medicare Advantage plans use provider networks — like HMOs or PPOs — which means your choice of doctors and facilities may be limited. Prior authorizations for certain treatments and specialist visits are also common. The trade-off is that these plans often come with lower monthly premiums, sometimes as low as $0, and many include extra benefits like dental, vision, and hearing coverage that Original Medicare doesn’t offer.

Here’s an important rule to know: you cannot have both a Medigap plan and a Medicare Advantage plan at the same time. They serve different purposes and are designed for different coverage paths.

• Medigap strengths: Provider freedom, predictable out-of-pocket costs, no network restrictions
• Medicare Advantage strengths: Lower premiums, potential extras like dental and vision coverage

Neither option is universally better. The right choice depends on your personal health needs, how often you see specialists, your budget, and your lifestyle preferences. Talking through both options with an experienced advisor can help you find the path that fits your unique situation.

What Medigap Does NOT Cover

Medigap plans are designed to fill the cost-sharing gaps in Original Medicare — but they aren’t all-in-one coverage. It’s just as important to understand what these plans don’t cover as it is to know what they do. Knowing the limits helps you plan for the full picture of your healthcare needs.

No Medigap plan covers any of the following:

• Prescription drugs — You’ll need a separate Medicare Part D plan for drug coverage. This is actually a very common pairing: many people carry a Medigap plan alongside a standalone Part D plan to cover both medical costs and medications.
• Dental care — Routine checkups, cleanings, and dental procedures are not included.
• Vision care — Eye exams, glasses, and contact lenses fall outside of Medigap coverage.
• Hearing aids — Neither the devices nor the fittings are covered under any Medigap policy.
• Long-term care services — Custodial care, such as help with bathing, dressing, or daily activities in a nursing home or at home, is a separate coverage need entirely. If this is a concern for you or a loved one, it’s worth learning about long-term care insurance as a dedicated solution.
• Private-duty nursing — One-on-one nursing care arranged privately is not a covered benefit.

None of these gaps make Medigap a poor choice — they simply reflect how the coverage is structured. Being aware of what’s missing allows you to explore the right combination of plans to meet your overall needs.

How to Choose the Right Medigap Plan

Picking the right Medicare supplement insurance plan doesn’t have to be overwhelming. The key is matching your coverage to your actual healthcare needs and budget — both today and in the years ahead. Here’s a practical framework to guide your decision.

1. Start With Your Healthcare Habits

Think honestly about how often you use medical services. If you visit doctors frequently, take regular specialist appointments, or have a history of hospitalizations, a more comprehensive plan like Plan G may be worth the higher monthly premium. On the other hand, if you’re generally healthy with few medical visits, Plan N or the cost-sharing plans like Plan K or L could give you meaningful savings without leaving you exposed to major costs.

2. Compare Premiums for the Same Plan Letter

Because Medigap plan benefits are standardized by the federal government, a Plan G from one insurer covers exactly the same services as a Plan G from another. This means you can — and should — compare premiums across multiple insurance companies for the same plan letter. Prices can vary significantly, so shopping around pays off. The Medicare.gov Medigap Plan Finder is a helpful starting point.

3. Evaluate the Insurer’s Financial Stability and Rate History

Look into each insurer’s financial strength ratings and their history of premium increases. While no one can guarantee future rate changes, companies with stable pricing histories are generally a safer long-term bet.

4. Understand How Your Plan Is Rated

Pay attention to whether a plan uses attained-age rating. These plans may start with lower premiums but can become significantly more expensive as you age. Issue-age and community-rated plans often offer more pricing stability over time.

5. Know Your State’s Protections

Some states have additional consumer protections or offer unique plan options beyond the federal standard. The NAIC Medicare Supplement Insurance resources can help you understand what applies in your state.

6. Work With an Independent Advisor

An independent insurance advisor can compare options across multiple carriers without being tied to one company’s products. This unbiased perspective can save you both money and stress — especially when the choices feel complex.

Taking the Next Step

Navigating Medicare on your own can feel overwhelming, but it doesn’t have to be. Medicare supplement insurance is one of the most effective tools retirees have for managing healthcare costs with real confidence and predictability. When you know your out-of-pocket exposure is controlled, you can focus on your health — not your bills.

If you’re approaching 65, the single most important window to know about is your Medigap Open Enrollment Period. During this six-month window, you have guaranteed issue rights, meaning insurance companies cannot deny you coverage or charge you more based on your health history. Once that window closes, your options may become more limited depending on where you live and your current health status.

That’s why understanding your choices before a health event occurs puts you in a far stronger position. The time to learn about Medicare supplement insurance is when you have the most flexibility — not after you’ve received a difficult diagnosis or a surprising medical bill.

Working with an independent insurance advisor means you get an honest look at the full range of options available to you, without being steered toward a single company’s products. At Akston Insurance, our team is here to help you understand what each plan covers, how the costs compare, and which approach fits your retirement goals.

If you have questions or simply want to talk through your Medicare options, we’d love to hear from you. Reach out to the Akston Insurance team — we’re happy to help you move forward with clarity.