What Is Medicare Supplement Insurance (Medigap)?
If you’ve recently enrolled in Medicare — or you’re getting close to age 65 — you’ve probably noticed something troubling: Original Medicare doesn’t cover everything. There are deductibles, copayments, and coinsurance gaps that can add up fast. That’s exactly where Medicare Supplement Insurance, commonly called Medigap, comes in.
Medigap is a private health insurance policy sold by insurance companies to fill the "gaps" in Original Medicare (Part A and Part B). It can cover costs like hospital coinsurance, skilled nursing facility costs, and sometimes even Part A deductibles — depending on the plan you choose.
According to the Kaiser Family Foundation, nearly 14 million Americans are enrolled in some form of Medigap coverage. That’s roughly 23% of all Medicare beneficiaries — and for good reason. A single hospital stay can trigger thousands of dollars in out-of-pocket costs under Original Medicare alone.
Medigap plans are standardized by the federal government, meaning a Plan G from one insurance company offers the exact same core benefits as a Plan G from another. What varies is the monthly premium you pay.
These plans do not work with Medicare Advantage (Part C). You must be enrolled in Original Medicare (Parts A and B) to qualify for a Medigap policy.
How Medigap Works: The Core Mechanics
Understanding how Medigap interacts with Medicare is critical before you buy. Here’s how the payment flow works in practice:
- You receive a medical service covered by Medicare.
- Medicare pays its share — typically 80% of approved costs for Part B services.
- Your Medigap policy pays some or all of the remaining 20%, depending on your plan.
- You pay little to nothing out of pocket, depending on your plan type.
Medigap plans are labeled with letters: A, B, D, G, K, L, M, and N. Plans C and F are still available but only to those who became eligible for Medicare before January 1, 2020.
Plan G is currently the most popular option for new Medicare enrollees. It covers nearly everything except the Part B deductible, which in 2026 sits at $257 per year. Plan N is another popular lower-premium alternative that requires modest copayments for some office visits.
One key rule: Medigap policies cover one person only. If both you and your spouse need coverage, you’ll each need a separate policy.
Key Benefits of Medigap Coverage
The financial protection that Medigap provides goes beyond convenience. Here’s what makes it genuinely valuable for many retirees:
Predictable Out-of-Pocket Costs
Original Medicare has no annual out-of-pocket maximum — meaning your costs are theoretically unlimited if you face a serious illness. Medigap eliminates most of that unpredictability. With Plan G, for example, your biggest annual cost is that $257 Part B deductible. Everything else is largely covered.
Freedom to Choose Any Medicare-Accepting Provider
Unlike Medicare Advantage, Medigap doesn’t use networks. You can see any doctor or specialist in the country who accepts Medicare — no referrals required, no network restrictions. This is a major advantage if you travel frequently or split time between states.
Guaranteed Renewability
As long as you pay your premiums, your Medigap insurer cannot cancel your policy due to health changes. That’s federal law. Your coverage is guaranteed renewable for life.
Hospitalization Protection
Medicare Part A covers hospital stays but comes with a deductible of $1,676 per benefit period in 2026. Most Medigap plans cover that deductible in full. For someone hospitalized multiple times in a year, this alone can save thousands of dollars.
According to the Federal Reserve’s 2025 Report on the Economic Well-Being of U.S. Households, 35% of adults aged 60 and older said a major unexpected expense would cause serious financial hardship. Medigap directly addresses that vulnerability.
How to Get Started: Step-by-Step Guide
Enrolling in Medigap at the right time can save you thousands and protect you from being denied coverage due to pre-existing conditions. Here’s how to do it correctly:
- Enroll in Medicare Parts A and B first. You must have Original Medicare before applying for Medigap. If you’re not yet enrolled, your Initial Enrollment Period begins 3 months before your 65th birthday and ends 3 months after.
- Identify your Medigap Open Enrollment Period (OEP). This is a 6-month window that starts the month you turn 65 AND are enrolled in Part B. During this period, insurers cannot deny you coverage or charge higher premiums due to health conditions. This is the most important window you have.
- Compare plans based on your health situation. If you use healthcare frequently, Plan G’s comprehensive coverage is likely worth the higher premium. If you’re generally healthy, Plan N’s lower premium with modest copays might be a better fit.
- Compare premiums across multiple insurers. Since benefits are standardized, shop aggressively on price. Use Medicare.gov’s Medigap policy search tool or work with an independent insurance broker who can compare multiple carriers.
- Check how the insurer prices premiums. There are three pricing methods:
- Community-rated: Same premium for everyone regardless of age.
- Issue-age-rated: Based on your age when you first buy — premiums don’t rise with age.
- Attained-age-rated: Based on your current age — premiums rise as you get older (most common, and most expensive long-term).
- Apply and enroll. Once you select a plan and insurer, complete the application. Your Medigap coverage typically begins the month after you enroll in Part B.
Costs, Fees, and Risks to Understand
Medigap isn’t free — and for some retirees, the costs may outweigh the benefits. Here’s the full picture:
Monthly Premiums
Premiums vary widely based on your age, gender, location, and the insurer. In 2026, Plan G premiums generally range from about $100 to $300+ per month for a 65-year-old, depending on the state and carrier. Plan N premiums tend to be 10–20% lower.
What Medigap Does NOT Cover
Even the most comprehensive Medigap plan doesn’t cover everything. Medigap policies typically exclude:
- Prescription drugs (you’ll need a separate Part D plan for that)
- Vision and dental care
- Hearing aids
- Long-term care
- Private-duty nursing
Premium Increases Over Time
If you’re on an attained-age-rated plan — the most common type — expect your premiums to increase as you age. Some beneficiaries find their premiums double between age 65 and 80.
Switching Plans Later Is Difficult
Outside of your Medigap OEP, insurers in most states can use medical underwriting — meaning they can deny you coverage or charge more based on pre-existing conditions if you try to switch plans. Guaranteed issue rights apply only in limited circumstances (like losing other coverage involuntarily).
This is why choosing the right plan from the start matters enormously. Rushing into a low-premium plan at 65 and trying to upgrade at 70 may not be possible — or could be prohibitively expensive.
Common Mistakes to Avoid
Many Medicare beneficiaries make costly errors when navigating Medigap. Here are the most common ones — and how to avoid them:
Mistake 1: Missing the Open Enrollment Period
This is the single most expensive mistake you can make. Enrolling outside your 6-month OEP means insurers can reject you or charge significantly higher premiums based on your health history. Mark this window on your calendar the moment you enroll in Medicare Part B. Missing it is not something you can undo.
Mistake 2: Choosing a Plan Based on Premium Alone
A lower monthly premium sounds attractive — but if you have frequent medical needs, a plan with higher out-of-pocket exposure could cost you far more annually. Run the math: compare total estimated annual costs (premium + expected out-of-pocket) not just the monthly premium.
Mistake 3: Confusing Medigap With Medicare Advantage
These are fundamentally different products. Medicare Advantage replaces Original Medicare; Medigap supplements it. You cannot have both simultaneously. Many retirees are sold Medicare Advantage plans without fully understanding they’ve given up Medigap eligibility — and getting back into Medigap later can be very difficult in most states.
Mistake 4: Ignoring the Insurer’s Financial Stability
Since benefits are standardized, many people focus only on price. But you also want an insurer with a strong financial rating (A or better from AM Best) and a history of manageable premium increases. A company that aggressively underprices premiums today may hike them dramatically in 5 years.
Mistake 5: Forgetting to Add Part D
Medigap covers medical costs — not prescription drugs. If you don’t enroll in a standalone Medicare Part D drug plan during your Initial Enrollment Period, you’ll face a lifetime late enrollment penalty of 1% of the national base beneficiary premium for every month you delay.
Alternatives to Medigap Worth Considering
Medigap isn’t the right fit for everyone. Here are three alternatives that might better match your situation:
1. Medicare Advantage (Part C)
Pros: Often has lower or $0 monthly premiums, includes Part D drug coverage, and may bundle dental, vision, and hearing benefits.
Cons: Restricted to provider networks, requires referrals in some plans, and out-of-pocket maximums can reach $8,850 or more in 2026. Best for relatively healthy people who prefer lower premiums and are comfortable with network restrictions.
2. Medigap Plan N (Budget-Conscious Option)
Pros: Lower premiums than Plan G — often 15–20% cheaper.
Cons: You’ll pay up to $20 per office visit and up to $50 for emergency room visits that don’t result in admission. Also doesn’t cover Part B excess charges (fees above Medicare-approved amounts). Good for healthier retirees who want solid protection with slightly more out-of-pocket flexibility.
3. High-Deductible Plan G
Pros: Very low monthly premiums — sometimes under $50/month for a 65-year-old.
Cons: You pay a $2,870 deductible (2026) before the plan kicks in. Best for people who are healthy, have significant savings to cover the deductible, and want a safety net for catastrophic costs only. This functions similarly to a high-deductible health plan in the pre-65 world.
If you’re navigating broader retirement financial decisions, you may also find it useful to revisit your asset allocation strategy as healthcare costs become a larger share of retirement spending.
Frequently Asked Questions
When can I enroll in Medigap without being denied for health reasons?
During your 6-month Medigap Open Enrollment Period, which starts the month you’re both 65 or older AND enrolled in Medicare Part B. During this window, insurers must sell you any plan they offer at standard rates — regardless of your health history.
How much does Plan G cost per month on average in 2026?
For a 65-year-old, monthly Plan G premiums typically range from $100 to $250+ depending on your state, gender, and the insurance company. Urban areas tend to have more competitive pricing. Using Medicare.gov’s comparison tool or working with an independent broker helps you find the best rates.
Can I have both Medigap and Medicare Advantage?
No. It’s illegal for an insurer to sell you a Medigap policy if they know you have Medicare Advantage. These two systems don’t work together. You must choose one or the other.
Does Medigap cover dental, vision, or hearing?
Generally no. Standard Medigap plans don’t cover dental, vision, or hearing. You would need separate standalone policies for those needs. Some insurers offer optional add-on riders, but coverage is limited.
What happens to my Medigap coverage if I move to another state?
Your Medigap policy generally travels with you anywhere in the country. Since Medigap works with Original Medicare — which is accepted nationwide — you can see any Medicare-accepting provider regardless of where you live or travel. However, your insurer may not be licensed in your new state, so you might need to switch to a different company offering the same plan letter.
Is Medigap Worth It? The Bottom Line
For most retirees — especially those managing chronic conditions, expecting frequent healthcare use, or simply wanting peace of mind — Medigap delivers real, measurable financial protection. The ability to budget predictably, see any Medicare doctor in the country, and avoid unlimited out-of-pocket exposure is worth a great deal in retirement.
That said, Medigap isn’t universally the best choice. If you’re in excellent health, have substantial savings, and are comfortable with network-based care, Medicare Advantage might offer more value at lower cost.
The most critical thing you can do is act during your Medigap Open Enrollment Period. Waiting costs you your guaranteed issue rights — and that’s a protection you cannot get back in most states.
Before finalizing your decision, consider speaking with a Medicare counselor through your State Health Insurance Assistance Program (SHIP) — a free, unbiased resource available in every state. And if your retirement finances need a broader review, building a solid sinking fund for healthcare expenses is a smart complement to any Medigap strategy.
This article is for educational purposes only and does not constitute financial, tax, or investment advice. Always consult a licensed financial advisor, CPA, or attorney before making financial decisions.