Medigap Insurance: What It Covers, When to Buy
How Medigap insurance fills the gaps in original Medicare, when the best time to buy it is, and how it differs from Medicare Advantage.
5 min read · 5 steps · Checked April 2026
Step 1. Understand what original Medicare leaves you to pay
Before deciding on Medigap, know what your out-of-pocket costs would be under original Medicare alone: the Part B deductible (about $240 in 2024), 20% of all outpatient services, and significant deductibles and coinsurance for hospital stays. If you have significant or ongoing medical needs, these costs can be substantial.
Quick Tip
Ask your doctor how often they expect you to need medical care in the next year. If it is frequent, a Medigap plan may pay for itself quickly.
Step 2. Start shopping during your Medigap Open Enrollment Period
Your Medigap Open Enrollment Period begins the first month you are 65 and enrolled in Part B, and lasts 6 months. During this window, insurers must accept you regardless of your health history. This is the only time you are guaranteed the right to buy any Medigap plan — do not miss it.
Warning
After this 6-month window, insurers in most states can reject you or charge much higher premiums based on your health. A few states (New York, Massachusetts, Connecticut) have continuous open enrollment — check your state's rules.
Step 3. Compare Plan G and Plan N for most new enrollees
Plan G covers nearly everything except the Part B deductible. Plan N covers everything Plan G covers except it has small copays (up to $20 for doctor visits, $50 for emergency room if not admitted) and does not cover Part B excess charges. Compare the premium difference between the two in your area — if Plan N's lower premium exceeds the likely copays, it may be the better value.
Step 4. Compare premiums between insurers at medicare.gov
Go to medicare.gov/plan-compare. Enter your zip code and select "Medigap policies." The same plan letter (e.g., Plan G) offers identical coverage at every company — the only variable is the monthly premium. Compare at least three insurers. A difference of $50/month is $600/year — worth taking seriously.
Step 5. Enroll and keep your Part D drug plan separate
Medigap does not include drug coverage. Once you choose a Medigap plan, also enroll in a standalone Medicare Part D prescription drug plan. You need both. Use the Plan Finder at medicare.gov to compare Part D plans based on your specific medications.
Quick Tip
Call your State Health Insurance Help Program (SHIP) for free, unbiased help comparing Medigap options. Find your local SHIP at shiphelp.org.
Original Medicare — Parts A and B — covers a lot. But it does not cover everything. You still pay a Part B deductible, 20% of most outpatient services, and significant cost-sharing for hospital stays. For people who see doctors regularly or have chronic health conditions, these out-of-pocket costs can add up to thousands of dollars a year.
Medicare Supplement insurance, commonly called Medigap, is sold by private insurance companies and fills in some or all of those gaps. You pay a monthly premium to the Medigap insurer, and in exchange, they pay all or most of your cost-sharing under original Medicare.
How Medigap works
Medigap plans are standardized by the federal government. In most states, plans are labeled by letters: Plan A, Plan B, Plan C, Plan D, Plan F, Plan G, Plan K, Plan L, Plan M, and Plan N. (Plan F is no longer available to new enrollees who became eligible for Medicare after January 1, 2020.)
Each plan letter covers the same benefits regardless of which insurance company sells it — the only difference between companies is the monthly premium. Plan G is currently the most comprehensive plan available to new enrollees.
What Medigap covers
Most Medigap plans cover: the Part A coinsurance and hospital costs, the Part B coinsurance (20%), blood transfusions, hospice coinsurance, and some cover the Part A and Part B deductibles. Most do NOT cover dental, vision, hearing, or prescription drugs. You still need a separate Part D drug plan.
Medigap vs. Medicare Advantage (Part C)
These are two different ways to supplement Medicare. Medigap works alongside original Medicare. You can see any doctor or hospital in the US that accepts Medicare, which is most of them. Medicare Advantage replaces original Medicare with a private plan that usually has lower premiums but requires you to use a specific network of providers.
The best time to buy Medigap
The best time to buy Medigap is during your Medigap Open Enrollment Period — the 6 months that begin the first month you are both 65 or older and enrolled in Part B. During this window, insurance companies must sell you a policy at the best available rate regardless of your health history. After this window closes, you can be denied or charged higher rates based on pre-existing conditions in most states.
Quick Tip: Compare Medigap premiums in your area at medicare.gov/plan-compare. The same standardized plan can vary by hundreds of dollars per month between insurers — shopping around is worth the time.
Official sources
- Medicare.gov — medicare.gov
- SSA.gov — ssa.gov
- IRS.gov — irs.gov
- USA.gov — usa.gov
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