What Is Medicare Supplement
Medicare Supplement insurance — commonly called Medigap — is a private health policy that pays for the "gaps" in Original Medicare (Part A and Part B), such as
Medicare Supplement insurance — commonly called Medigap — is a private health policy that pays for the "gaps" in Original Medicare (Part A and Part B), such as copayments, coinsurance, and deductibles. It does not replace Medicare; it works alongside it, stepping in as the secondary payer after Medicare pays its share. If you are enrolled in Original Medicare and want to reduce your out-of-pocket exposure, a Medigap policy can give you predictable, near-complete coverage at doctor visits, hospital stays, and other approved services.
How Medicare Supplement Coverage Works
Original Medicare covers hospital care (Part A) and outpatient services (Part B), but it comes with significant cost-sharing. For example, in 2024, the Part A deductible is about $1,632 per benefit period, and the Part B deductible is about $240. After those deductibles, you still face coinsurance — 20% of the Medicare-approved amount for most Part B services — with no cap on that amount. A Medigap policy is designed to absorb these expenses, depending on which plan you choose.
Medigap policies are sold by private insurance companies, but the federal government standardizes the benefits within each plan letter (A, B, C, D, F, G, K, L, M, and N). That means a Plan G from one insurer offers the same basic benefits as a Plan G from another, even though the monthly premium may differ. Importantly, a Medigap policy only covers one person; if both spouses need coverage, each must buy a separate policy. Also, Medigap does not cover prescription drugs — you would need a separate Part D plan — and it does not cover vision, dental, or long-term care.
To buy Medigap, you must be enrolled in both Medicare Part A and Part B. The policy reimburses you for your share of Medicare-covered services, but it cannot be used as a standalone plan. You still pay your Part B monthly premium (roughly $174.70 per month for most beneficiaries in 2024) on top of the Medigap premium.
The Standardized Medigap Plans: What Each Covers
Medicare Supplement plans are labeled with letters, and each letter offers a different level of coverage. Some plans cover the Part A deductible, some cover Part B excess charges, and some include additional benefits like emergency foreign travel care (up to plan limits, typically $50,000 lifetime). Here is a simplified comparison of the most popular options:
| Plan | Core Gaps Covered | Typical Monthly Premium Range |
|---|---|---|
| Plan F | Covers all gaps, including the Part B deductible | $180–$350 |
| Plan G | Covers all gaps except the Part B deductible | $150–$300 |
| Plan N | Covers all gaps except Part B deductible and some copays | $120–$250 |
| Plan K | Covers about 50% of cost-sharing, with an out-of-pocket limit | $80–$150 |
Plan F was the most comprehensive Medigap option, but because of the Medicare Access and CHIP Reauthorization Act of 2015, it is no longer available to people who became eligible for Medicare after January 1, 2020. For newer beneficiaries, Plan G has become the most popular choice because it covers nearly everything except the relatively small Part B deductible. Plan N is a more budget-friendly option, but it requires small copays — up to $20 for an office visit and up to $50 for an emergency room visit (if you are not admitted).
Plans K and L have lower premiums but cap your out-of-pocket costs: in 2024, Plan K’s out-of-pocket limit is about $7,060, while Plan L’s is about $3,530. These plans are worth considering if you want a safety net but prefer lower monthly costs.
Costs and the Best Time to Buy Medigap
Your Medigap premium depends on your age, location, gender, smoking status, and the insurer's pricing method. Some insurers use attained-age pricing (premiums rise as you get older), while others offer issue-age pricing (premiums are based on your age when you buy, and they rise less steeply). In most states, you can expect to pay anywhere from $100 to $400 per month for Medigap coverage, with Plan G typically costing more than Plan N but less than the old Plan F.
The most important rule about Medigap is the Medigap Open Enrollment Period. This window opens on the first day of the month you are both 65 or older and enrolled in Medicare Part B, and it lasts for six months. During this time, you have guaranteed issue rights: insurers must sell you any Medigap policy in your state at the same price they charge others, regardless of your health history. If you buy outside this window, you will likely face medical underwriting, meaning the insurance company can review your medical records and may charge you more, deny you coverage, or delay coverage for pre-existing conditions. There are a few other guaranteed-issue situations, such as losing employer coverage or dropping a Medicare Advantage plan within your trial right period, but do not assume you will qualify for those.
If you delay enrolling in Original Medicare because you are covered by an employer plan, your Medigap open enrollment starts once you actually sign up for Part B at 65 or later. Missing this window is the most common reason people find Medigap unaffordable or unobtainable later in life.
Medigap vs. Medicare Advantage: Which Fits You?
Medicare Supplement is fundamentally different from Medicare Advantage (Part C), which is a privatized alternative to Original Medicare. Advantage plans bundle hospital and medical coverage into an HMO, PPO, or similar network plan, often include Part D drug coverage, and can charge low premiums. However, they impose networks, prior authorization, and an annual out-of-pocket maximum — typically between $4,000 and $9,000 for in-network care in 2024.
Medigap, by contrast, lets you see any doctor or hospital that accepts Medicare nationwide — no network gatekeepers. It has no annual out-of-pocket cap, but because it covers most cost-sharing for covered services, your main risk is the premium itself. Medigap also does not include Part D drug coverage, so you must purchase a standalone drug plan. In contrast, many Medicare Advantage plans combine medical and drug coverage in one policy.
Which is better depends on your priorities. If you travel frequently, want to avoid networks, and can afford a higher monthly premium, Medigap gives you the most predictable coverage. If you prefer a lower premium and are comfortable with managed care, Medicare Advantage may be appealing. Just remember: you cannot use a Medigap policy to pay for Medicare Advantage cost-sharing, so the two are strictly separate choices.
Frequently Asked Questions
Is a Medicare Supplement plan worth the monthly premium?
For heavy users of healthcare, yes — a single hospital stay or chronic condition can generate thousands of dollars in coinsurance that Medigap would cover. For low users, the premium might feel like a heavy expense. However, Medigap also provides financial predictability, which is its core value. If you value no surprise medical bills, it is generally worth it.
Can I use a Medigap policy with any doctor?
Yes. As long as the doctor or facility accepts Medicare assignment (most do), your Medigap policy will pay secondary benefits. There are no provider networks in Medigap, which is a major advantage over Medicare Advantage plans.
Does Medigap cover prescription drugs?
No. Policies sold after 2006 cannot include drug coverage. You must enroll in a separate Medicare Part D plan to cover outpatient prescription medications. You can get Part D on its own even if you have Medigap.
Choosing a Medicare Supplement policy comes down to understanding what Original Medicare leaves uncovered, what you can spend in monthly premiums, and when you buy. Review your state’s standardized plan options on Medicare.gov, compare premiums from several insurers, and prioritize your Medigap Open Enrollment Period to lock in guaranteed coverage. With the right plan, you can turn Original Medicare into nearly worry-free healthcare — no networks, no prior approvals, and no surprise coinsurance bills.