Medicare Parts A and B (known as original Medicare) don’t cover 100% of medical costs. Luckily, policyholders can get a Medigap plan (supplemental plan) to help cover those costs. By working alongside original Medicare and filling in the coverage gaps, Medigap makes your health care expenses more predictable. This guide explains what Medigap is, how the plans work, and how to compare the plan options.
What is Medigap?
Medigap is optional supplemental insurance you can purchase from a private insurer to help cover costs that original Medicare (Parts A and B) doesn’t pay. These gaps include coinsurance, copayments, deductibles, and sometimes emergency care while traveling abroad.
To understand this better, let’s quickly define a few key terms:
- Coinsurance: Your share of the costs for a Medicare-approved service. This is usually a percentage of the allowed amount, such as 20%.
- Copayment (copay): A set amount, like $20, that you pay for a covered service such as a prescription or doctor visit.
- Deductible: The amount you must pay out of pocket before original Medicare or your Medigap plan begins to pay.
One key reminder: Medigap is only for people who have original Medicare. If you’re enrolled in a Medicare Advantage plan (Part C), you cannot buy a Medigap policy.
Medigap plans are standardized for simplicity
One of the most powerful and consumer-friendly features of Medigap is that the different plans are standardized by federal law. There are 10 standardized plans, named with letters (A, B, C, D, F, G, K, L, M, and N). Standardization means that a Plan G policy covers the same medical benefits regardless of the company that sells it. The only possible differences among plans of the same letter are:
- The monthly premium.
- The insurance company’s customer service and reputation.
- Available discounts or extra features that some insurers might include.
This standardization provides a strong base for confidently comparing plans.
A quick eligibility note: Plans C and F are not available to people whose Medicare eligibility started on or after January 1, 2020. This is because a new law barred new Medigap policies from covering the Medicare Part B deductible (which Plans C and F do). If you were eligible before then, you may still buy those Medigap plans if insurers in your area offer them.
Your six-month Medigap open enrollment period
When you first enroll in Medicare Part B, you get a six-month Medigap open enrollment period. During that window, you are guaranteed access to any Medigap plan sold in your state, regardless of preexisting conditions. You are guaranteed:
- No medical underwriting.
- No higher premiums for those with health issues.
- No denials.
After those six months end, the landscape changes. Most people must then go through underwriting to buy or switch plans, and insurers can raise premiums or decline coverage based on medical history. This makes early decision-making especially important.
Overview of Medigap plans A through N
Here’s a simple overview of each plan. These aren’t complete benefit lists, but they can help you understand the differences quickly.
| Plan letter | Key benefits covered (in addition to basic benefits) | Notes on availability/cost |
| Plan A | The most basic plan. Covers only the most fundamental gaps. | All companies must offer this plan. Lowest-premium option. |
| Plan B | Basic benefits plus the Part A deductible. | Offers slightly more financial protection than Plan A. |
| Plan C | Full coverage for nearly everything, including the Part A deductible, Part B deductible, and foreign travel emergency. | Not available to those newly eligible for Medicare after Jan. 1, 2020. |
| Plan D | Offers the same full coverage as Plan C but does not cover the Part B deductible. Includes foreign travel emergency. | A comprehensive option for those new to Medicare starting in 2020. |
| Plan F | Offers 100% coverage for all gaps in original Medicare, including the Part B deductible, Part B excess charges, and foreign travel emergency. | Not available to those newly eligible for Medicare after Jan. 1, 2020. This was previously the most popular plan. |
| Plan G | Includes everything covered by Plan F except the Part B deductible. | The most popular and comprehensive plan available to new Medicare beneficiaries. |
| Plan K | Pays 50% of most out-of-pocket costs until you reach an annual out-of-pocket limit, then pays 100%. Does not pay the Part B deductible, Part B excess charges, or foreign travel emergency. | Lower premium, but you’ll pay more out of pocket until you hit the limit. |
| Plan L | Offers similar coverage to Plan K, except it pays 75% instead of 50% of most out-of-pocket costs until you reach an annual out-of-pocket limit, then pays 100%. Has the same exclusions. | Higher percentage coverage than Plan K, with an annual out-of-pocket limit. |
| Plan M | Similar to Plan G, but only pays 50% of the Part A deductible and does not pay the Part B excess charges. | Offers a middle ground between low and high coverage. |
| Plan N | Similar to Plan M, but pays 100% of the Part A deductible. May require copayments for some office visits and some emergency room visits. | A popular low-premium option for people who don’t mind small copays. |
A note on Part B excess charges: Part B excess charges are important, yet they are often overlooked when evaluating Medigap plans. If a doctor doesn’t accept the Medicare-approved amount, called accepting assignment, they can legally charge you up to 15% more than the Medicare-approved amount. Medigap plans F and G are the only plans that cover this charge, which is a key reason why they are often preferred for controlling total costs.
How to compare Medigap plans: Premiums vs. coverage
Choosing a Medigap plan is both a financial choice and part of a long-term health plan. While premiums matter, so does your comfort level with uncertainty.
Premiums differ for various reasons, including:
- Your age and ZIP code.
- How the insurer prices its plans (the three rating mechanisms are community-rated, issue-age-rated, or attained-age-rated).
- Discounts (for multiple household members, nonsmokers, and automatic payment).
- The specific plan letter.
Why your choice at 65 matters more than many realize: At age 65, you can’t predict what your health care needs will be in 10, 20, or 30 years. Because switching Medigap plans later usually requires medical underwriting, it can be difficult or costly to move into a more comprehensive plan if your health declines.
This restriction is why many people choose a strong plan early on, especially Plan F (before 2020) and Plan G (after 2020), because it’s easier to start with more protection than to try to upgrade later.
When paying a higher premium makes sense: A more expensive plan may be right for you if you want:
- Predictable yearly medical costs.
- Complete protection.
- Fewer surprises at the point of care.
When a lower premium might be more suitable: Consider lower premiums if you:
- Want to keep monthly costs down.
- Are comfortable paying more when you use services.
- Visit doctors infrequently.
- Prefer a safety net over full coverage.
Medigap plans like K, L, and sometimes N often appeal to people who are comfortable with more cost-sharing.
Where to learn more and compare plans
Once you’re ready to look at actual premiums and companies in your area, here are the places to begin:
- Medicare.gov’s Medigap plan finder lets you compare plans and pricing by ZIP code.
- Your State Health Insurance Assistance Programs (SHIPs) provide free, unbiased guidance.
- Your state’s Department of Insurance can help you check pricing rules, complaint histories, and consumer protections.
- ElderLife Financial can walk you through your options, review your long-term projections, and help ensure your Medigap choice aligns with your overall retirement plan.
Medigap can make Medicare more predictable and reliably manageable. By understanding the standardized plans, knowing your enrollment rights, and comparing options thoughtfully, you can choose a plan that supports both your health and your financial peace of mind for years to come.
