Medicare Supplement Plans

Medicare Supplement insurance (Medigap) fills the gaps that Original Medicare leaves behind — copayments, coinsurance, deductibles, and excess charges that can add up fast. If you have Medicare Part A and Part B, a Medigap policy from a private insurer pays some or all of those remaining costs, giving you predictable out-of-pocket expenses and the freedom to see any provider that accepts Medicare.

There are 10 standardized plan letters to choose from, each covering a different combination of benefits. Below, we break down exactly what each plan covers, how to choose the right one, and when to enroll to lock in the best rates.

How Medicare Supplement Plans Work with Original Medicare

Medigap policies are designed to work alongside Original Medicare — not replace it. You must be enrolled in both Medicare Part A and Part B before you can buy a Medigap plan. Here is how the payment process works:

1. You receive medical care from any doctor or hospital that accepts Medicare (no network restrictions).
2. Medicare pays its share of the approved amount.
3. Your Medigap plan pays some or all of the remainder — copayments, coinsurance, or deductibles — depending on which plan letter you have.

Unlike Medicare Advantage, Medigap plans do not include prescription drug coverage. If you need drug coverage, you will need to enroll in a separate Medicare Part D plan. Comparing the best Part D options alongside your Medigap choice ensures complete coverage.

The 10 Standardized Medicare Supplement Plan Letters

Every Medigap plan sold in most states is standardized by the federal government, meaning Plan G from one insurance company covers exactly the same benefits as Plan G from another. The only differences between insurers are price, customer service, and financial stability. Here is what each plan covers:

Note: Massachusetts, Minnesota, and Wisconsin use their own standardized plan structures instead of the letter system above.

Key Benefits of Having a Medigap Policy

1. Predictable costs: With most plans, you know exactly what your out-of-pocket maximum will be each year — in many cases, zero beyond your monthly premium.
2. Freedom to choose any provider: Medigap has no networks. You can see any doctor or visit any hospital that accepts Medicare, anywhere in the country.
3. No referrals needed: You do not need a primary care doctor's referral to see a specialist. This is especially valuable for people managing conditions like heart disease who see multiple providers.
4. No claim forms: Medicare and your Medigap insurer handle the billing between themselves.
5. Coverage travels with you: Unlike many Medicare Advantage plans, Medigap works nationwide. Some plans also include foreign travel emergency coverage.

How to Choose the Right Medicare Supplement Plan

Choosing between Medigap plans comes down to balancing monthly premium costs against potential out-of-pocket risk. Here is a practical framework:

If you want maximum coverage and minimal surprises: Plan G is the go-to choice for most new enrollees. It covers virtually all gaps except the annual Part B deductible (which is $257 in 2025). For a detailed comparison, see our breakdown of Plan G vs. Plan N.

If you want lower premiums and are comfortable with small copays: Plan N offers solid coverage at a lower monthly cost. You will pay up to $20 for some office visits and up to $50 for ER visits that do not lead to hospital admission, but your premiums could be $30-$60 less per month than Plan G. Our breakdown of 2026 Plan N prices shows what you can expect to pay by region.

If you want the lowest possible premium: High-Deductible Plan G keeps your monthly cost very low. You pay the first $2,870 of covered expenses each year, then the plan covers everything. This works well for healthy beneficiaries who rarely use medical services.

If you became Medicare-eligible before 2020: You may still be able to enroll in Plan F or Plan C, which are no longer available to newer enrollees. Plan F covers everything including the Part B deductible.

Medicare Supplement Costs and Pricing

Medigap premiums vary significantly based on several factors:

• Your age: Most policies use attained-age rating, meaning premiums increase as you get older. Some use issue-age or community rating — these tend to be more stable over time.
• Your location: Premiums differ by state and even by zip code.
• The insurance company: Because benefits are standardized, the same plan can cost very different amounts from different insurers. Shopping around is essential.
• Tobacco use and gender: Some states allow insurers to factor in tobacco use and gender when setting premiums.
• Household and payment discounts: Many insurers offer discounts for married couples, auto-pay, or annual payment.

For current pricing data, see our analysis of 2026 Plan G prices across the country.

When to Enroll: Medigap Open Enrollment and Guaranteed Issue

The single most important enrollment window for Medigap is your Medigap Open Enrollment Period. This is a one-time, 6-month window that starts the month you turn 65 and are enrolled in Medicare Part B. During this period:

• Insurance companies cannot deny you coverage for any reason.
• They cannot charge you more because of health conditions.
• You can buy any Medigap plan sold in your state.

After this window closes, insurers can use medical underwriting — they can deny coverage or charge higher premiums based on your health history. This makes enrolling during your open enrollment period critical. For full details on timing and eligibility, read our guides on Medicare Supplement enrollment periods and Medicare Supplement eligibility.

Medicare Supplement vs. Medicare Advantage

Many people compare Medigap to Medicare Advantage when deciding how to structure their Medicare coverage. Here are the key differences:

Neither option is universally better — the right choice depends on your health needs, budget, preferred doctors, and how often you travel. For a deeper comparison, read our guide on comparing Medicare coverage options.

Frequently Asked Questions

Can I have both a Medigap plan and a Medicare Advantage plan?
No. Federal law prohibits insurance companies from selling you a Medigap policy if you are enrolled in a Medicare Advantage plan. You must choose one or the other.

Does Medigap cover prescription drugs?
No. Medigap plans sold after 2006 do not include prescription drug coverage. You will need a separate Medicare Part D plan for drug coverage.

Can I switch Medigap plans later?
You can apply to switch plans at any time, but outside your initial open enrollment period, you may be subject to medical underwriting. Don't fall for common Medicare myths about when you can and can't switch. Some states have additional protections — check your state's rules.

What if I have questions about which plan is right for me?
Speaking with a local Medicare insurance agent is one of the best ways to get personalized guidance at no cost to you. Licensed agents can compare plans and prices in your area.