- Differences
- Which is better?
- Switching plans
- Enrollment periods
- Summary
An individual cannot have a Medicare Advantage (Part C) plan and a Medicare supplement insurance plan, also called a Medigap plan, at the same time. If a person with a Medigap plan joins Medicare Advantage, they will no longer be able to use the Medigap coverage.
Medicare typically provides insurance coverage for adults ages 65 years and over. Plans are available through either Original Medicare (parts A and B) or Medicare Advantage (Part C).
Some people with Original Medicare can also take out a private supplemental policy called Medigap. It helps them pay for out-of-pocket costs, such as deductibles and coinsurance.
Private insurers administer both Medicare Advantage and Medigap, so these plans share a complex relationship. Having one means that a person may not be able to use the other. Read on to learn more.
Glossary of Medicare terms
- Out-of-pocket cost: This is the amount a person must pay for care when Medicare does not pay the total amount or offer coverage. Costs can include deductibles, coinsurance, copayments, and premiums.
- Premium: This is the amount of money someone pays each month for Medicare coverage.
- Deductible: This is an annual amount a person must spend out of pocket within a certain period before Medicare starts to fund their treatments.
- Coinsurance: This is the percentage of treatment costs that a person must self-fund. For Medicare Part B, coinsurance is 20%.
- Copayment: This is a fixed dollar amount a person with insurance pays when receiving certain treatments. For Medicare, this usually applies to prescription drugs.
Medicare Advantage (Part C) plans combine coverage from parts A and B. They also allow people to access extra services that Original Medicare may not cover, such as dental, hearing, or vision care.
Medigap is supplemental insurance. Medigap enrollees pay a monthly premium to cover out-of-pocket costs of Original Medicare.
People with a Medicare Advantage plan cannot buy a Medigap plan.
People who already have a Medigap plan may technically be able to get a Medicare Advantage plan if they choose to switch coverage. However, many people choose to leave their Medigap plan after joining Medicare Advantage because they will no longer be able to use the Medigap benefits.
Medigap pays for many costs that Original Medicare does not. Medicare Advantage, on the other hand, replaces Original Medicare and often offers additional coverage.
Medicare Advantage usually includes Part D, or prescription drug coverage. Medigap does not usually include Part D coverage.
Choosing a Medicare Advantage plan depends entirely on a person’s individual needs and medical requirements. Each plan has several aspects that may be more suitable for some people than others.
The following table compares the benefits and drawbacks of Medicare Advantage and Medigap:
| Medicare Advantage | Medigap | |
|---|---|---|
| Coverage | often includes additional benefits, such as vision, dental, and hearing | covers gaps in Original Medicare, such as copayments and deductibles |
| Network providers | limited to healthcare professionals within fixed provider networks | permits care at any provider who accepts Medicare |
| States | offers coverage only in the individual’s state and region | provides coverage in any state |
| Costs | has lower premiums but may have higher out-of-pocket costs | has higher premiums, but fewer out-of-pocket costs |
| Flexibility | offers less flexibility due to network restrictions | offers more flexibility in choosing healthcare professionals |
People who want to switch from Medicare Advantage to Original Medicare with Medigap will need to contact their insurance provider to check whether their plan allows them to disenroll.
If an individual has Medigap, they may join Medicare Advantage with a 12-month trial period. During this time, they can get Medigap back with the same insurer, as long as the insurer still sells Medigap policies.
It is important to note that Medigap plans sold after 2005 do not cover drug prescriptions.
People can join a Medicare Advantage or Medigap plan only during certain windows, known as enrollment periods.
Medicare Advantage
The Medicare initial enrollment period (IEP) is 3 months before a person turns 65 years old, during their birthday month, and 3 months afterward.
An individual can join a Medicare Advantage (Part C) plan during this time as long as they have Medicare Part A, which covers in-hospital treatment, and Part B, which covers outpatient care.
For people who have Part A but join Part B after coverage starts, the IEP starts 3 months before Part B begins.
A general open enrollment period (OEP) runs from October 15 to December 7. During the OEP, a person can drop an existing Medicare Advantage plan, switch to another Advantage plan, or switch back to Original Medicare.
The Medicare Advantage OEP is from January 1 to March 31. During this time, a person can switch to a different Medicare Advantage plan or return to Original Medicare.
Medigap
Medigap has a 6-month OEP that starts the month after a person gets Medicare Part B and is at least 65 years old.
Some states may offer Medigap to people under age 65 years if they have Part B due to disability or end stage renal disease (ESRD). This is not the case in every state, though.
Applying for Medigap outside of the OEP may mean:
- a person has limited options for policies
- policies may cost more
- the plan provider can deny coverage based on preexisting medical conditions
Medicare resources
For more resources to help guide you through the complex world of medical insurance, visit our Medicare hub.
A person cannot use Medicare Advantage (Part C) and Medigap at the same time. If a person already has Medicare Advantage, they cannot enroll in Medigap.
Those looking to take out a Medicare Advantage plan may need to leave their Medigap policy, as they will no longer be able to use their Medigap insurance.
Individuals looking to switch from one to the other should check the rules on disenrollment for that particular policy with their insurance provider, as private insurers administer these policies.
Last medically reviewed on June 16, 2025
- Health Insurance / Medical Insurance
- Medicare / Medicaid / SCHIP
