How Medigap works
Medigap is private insurance that works alongside Original Medicare. Medicare pays its share of approved costs first, then Medigap pays some or all of what’s left. Medigap policies sold since 2006 don’t include drug cover, so you also need a Part D plan. Medigap can’t be used with Medicare Advantage.
The standardized plans
Most states offer up to 10 plans: A, B, C, D, F, G, K, L, M and N. Massachusetts, Minnesota and Wisconsin standardize plans differently. Plans C and F, which cover the Part B deductible, can’t be sold to people who became eligible for Medicare on or after January 1, 2020.
| Plan | What it’s known for | Main costs you still pay |
|---|---|---|
| Plan G | Most comprehensive plan for new enrollees; about 39% of buyers in 2023 | Part B deductible ($283 in 2026) |
| High-deductible Plan G | Lower premium in exchange for a deductible | Annual deductible before benefits start |
| Plan N | Lower premium than G | Part B deductible, some copays for office and ER visits, and Part B excess charges |
| Plans K and L | Cost-sharing plans with an annual out-of-pocket limit | A share of costs until the limit |
| Plan F | Covers the Part B deductible too | Only for people eligible before 2020 |
Sources: Medicare.gov; NerdWallet (citing AHIP).
What Medigap costs
Premiums depend on the plan letter, your age, sex, smoking, ZIP code and the insurer’s pricing method. They start from about $40 a month. NerdWallet’s example for a 65-year-old nonsmoking woman in Atlanta: Plan G from about $129 a month, high-deductible Plan G from $44 and Plan K from $66.
Insurers price in one of three ways: community-rated (same price regardless of age), issue-age-rated (based on age when you buy) or attained-age-rated (rising as you get older). A cheap attained-age policy at 65 can become expensive at 80, so ask how premiums are set.
When to buy: the six-month window
Your Medigap Open Enrollment Period lasts six months, starting the first month you have Part B and are 65 or older. It happens once. During it, insurers must sell you any policy they offer in your state at their standard price, with no medical underwriting. After it ends, insurers in most states can refuse you or charge more based on your health, except in specific guaranteed-issue situations such as your Medicare Advantage plan leaving your area or your trial right to return within 12 months of first trying Medicare Advantage.
That’s why the choice between Medigap and Medicare Advantage at 65 matters; see Medicare Advantage vs. Original Medicare.
How to buy
- Choose the plan letter that fits your budget and health.
- Get quotes from several insurers for the same letter; benefits are identical, so price and service are what differ.
- Ask how the policy is rated and about its rate-increase history.
- Add a Part D drug plan; see our Part D guide.
- Get free help from your SHIP counselor (1-877-839-2675).
For full cost figures, see Medicare costs.
Frequently asked questions
What is the most popular Medigap plan?
Plan G, chosen by about 39% of Medigap buyers in 2023. It covers everything Original Medicare leaves except the Part B deductible.
When is the best time to buy Medigap?
During your six-month Medigap Open Enrollment Period, which starts the first month you have Part B and are 65 or older. Insurers can’t turn you down then.
Does Medigap cover prescription drugs?
No. Policies sold since 2006 don’t cover drugs, so you need a separate Part D plan.
Can I still buy Medigap Plan F?
Only if you were eligible for Medicare before January 1, 2020.
How much does Medigap cost?
From about $40 a month, depending on the plan, your age and where you live. A 65-year-old might pay around $129 a month for Plan G in some areas.
Sources
- Medicare.gov – Medigap guaranteed issue rights
- Medicare.gov – Medigap and Medicare Advantage
- NerdWallet – What to know about Medigap
- Medicare.gov – Medicare costs
- NCOA – State Health Insurance Assistance Program (SHIP)
Insurance prices, discounts and rules change often and vary by state. Figures were checked in October 2026; confirm details with the insurer or your state insurance department.