Medigap is Medicare Supplement insurance sold by private insurers to help pay certain costs left by Original Medicare, such as coinsurance, copayments and deductibles. It supplements Parts A and B. It is not a Medicare Advantage plan and does not pay Medicare Advantage cost-sharing.
How the payments work
For a covered service, Original Medicare pays its share first. Your Medigap policy then pays the amounts included in its benefits. You remain responsible for costs neither coverage pays. Generally, you need both Part A and Part B to buy Medigap, and you pay a separate premium for the policy in addition to your Part B premium.
A Medigap policy covers one person. A couple who both want it need separate policies. Standardized policies are guaranteed renewable when you meet their conditions; a new health problem alone does not allow the insurer to cancel your policy. Premiums can still change.
Covered costs and important exclusions
| Category | What to know |
|---|---|
| Original Medicare cost-sharing | The plan letter determines which deductibles, coinsurance and copayments it helps pay. |
| Foreign travel emergencies | Some plans have a limited benefit, subject to deductible, time and lifetime limits. |
| Routine dental, vision and hearing aids | Generally not included in standardized Medigap benefits. |
| Long-term custodial care | Generally not covered by Medigap. |
| Part D coverage | Medigap policies sold after 2005 do not include prescription coverage; review Part D separately. |
Compare the plan letter before the company
In most states, policies with the same letter provide the same standardized benefits even when sold by different insurers. Premiums, service and any nonstandard extras can differ. Massachusetts, Minnesota and Wisconsin use different standardization systems. Plans C and F are not available to people newly eligible for Medicare on or after January 1, 2020; people eligible earlier may still be able to buy them.
Enrollment timing protects your choices
The federal six-month Medigap Open Enrollment Period starts the first month you are 65 or older and enrolled in Part B. During that period, an insurer cannot refuse to sell an available policy or charge more because of health problems, subject to the plan eligibility rules. A pre-existing-condition waiting period can still apply in certain cases; prior creditable coverage can reduce or eliminate it.
Afterward, an insurer may use medical underwriting unless you have a guaranteed issue right or applicable state protection. The fall Medicare Open Enrollment Period does not create a general annual right to buy Medigap. Do not cancel existing coverage before confirming your acceptance, start date and rights.
Use this comparison checklist
- Confirm the plan letter and standardized benefits for your state.
- Ask for the premium, pricing method and any available discounts.
- Check remaining deductibles, copayments and excess charges.
- Confirm your enrollment protection and any waiting period.
- Review separate coverage needs and the total monthly cost.
Related coverage questions
- How to Compare Medigap Policies
- Medigap Comparison Chart: Benefits and 2026 Cost Limits
- Your Medigap Open Enrollment Period