Medicare Advantage replaces your Original Medicare coverage, but you keep your Medicare card and may be able to access
When you enroll in a Medicare Advantage plan, you are switching from Original Medicare (Parts A and B) to a private insurance plan that covers the same services. You do not lose your Medicare status—you are still enrolled in Medicare. What changes is who delivers your coverage: instead of the federal government paying doctors and hospitals directly, a private insurance company (like Humana, United, or Anthem) manages your benefits and pays providers.
You keep your red, white, and blue Medicare card. You use it to prove you have Medicare. But when you see a doctor, you show your Medicare Advantage plan card instead, and the private plan handles the claim. If you ever drop the Medicare Advantage plan and go back to Original Medicare, your federal coverage picks up again without a gap—as long as you stay enrolled in Medicare Part B.
Key Takeaways
- Medicare Advantage is a private insurance plan that replaces Original Medicare coverage; you switch from federal coverage to a private company's plan.
- You must stay enrolled in Medicare Part B to have a Medicare Advantage plan, and you pay the Part B premium to Medicare plus any plan premium to the insurance company.
- Medicare Advantage plans often cost less in monthly premiums than Original Medicare plus a Medigap policy, but they use networks and may require prior approval for some services.
- You can switch back to Original Medicare during the annual open enrollment period (October 15 to December 7) or if you move out of the plan's service area.
- If you have a Medigap policy when you enroll in Medicare Advantage, you should cancel it because Medicare Advantage and Medigap do not work together.
What happens to your Original Medicare coverage when you enroll in Medicare Advantage
The moment your Medicare Advantage plan becomes active, your Original Medicare coverage ends. Medicare Part A (hospital insurance) and Part B (medical insurance) stop paying claims. Instead, the private plan pays for hospital stays, doctor visits, lab work, and other services covered under Parts A and B. You do not have two plans running at once—you have one or the other.
This is different from adding a Medigap policy to Original Medicare. With Medigap, you keep Original Medicare as your primary payer and the Medigap policy covers what Medicare does not. With Medicare Advantage, the private plan is your only payer for Part A and B services. If you have a Medigap policy when you switch to Medicare Advantage, that Medigap policy becomes useless and you should cancel it to stop paying the premium.
How your costs change under a Medicare Advantage plan
You still pay the Part B premium to Medicare each month (the standard amount is deducted from Social Security or billed directly). On top of that, you may pay a monthly premium to the Medicare Advantage plan itself—though many plans charge zero premium. You also pay copays when you see a doctor or fill a prescription, and you may have an annual deductible before the plan starts paying.
The trade-off is that Medicare Advantage plans often cost less in total monthly premiums than Original Medicare plus a Medigap policy would. However, you are responsible for all copays and deductibles, and you must use doctors and hospitals in the plan's network. If you see an out-of-network provider without a referral, you may pay the full bill yourself. Original Medicare has no network—you can see any doctor who accepts Medicare.
Network restrictions and prior approval requirements
Most Medicare Advantage plans are HMO (Health Maintenance Organization) or PPO (Preferred Provider Organization) plans. HMO plans require you to choose a primary care doctor and get referrals to see specialists. PPO plans let you see specialists without a referral but charge more if you go out of network. Both types restrict you to in-network providers in most cases.
Medicare Advantage plans also often require prior approval before you have certain procedures, imaging tests, or hospital stays. Your doctor's office usually handles this request, but it can delay treatment by a few days. Original Medicare does not require prior approval for most services—your doctor orders the test and Medicare pays for it.
Prescription drug coverage under Medicare Advantage
Most Medicare Advantage plans include prescription drug coverage (Part D) built in. You do not enroll in a separate Part D plan. The plan covers both brand-name and generic drugs, though you may pay different copays depending on which tier the drug is on. Some drugs may not be covered, or you may need prior approval to fill them.
If you have Original Medicare and want drug coverage, you must enroll in a separate Part D plan during the annual open enrollment period or when you first become may be able to access. With Medicare Advantage, the drug coverage is included, which can simplify your coverage and sometimes cost less.
When you can switch back to Original Medicare
You can drop your Medicare Advantage plan and return to Original Medicare during the Annual Enrollment Period, which runs from October 15 to December 7 each year. Changes take effect January 1. You can also switch if you move out of the plan's service area, lose plan coverage, or experience certain may have access to life events.
If you switch back to Original Medicare, you have a 63-day window to enroll in a Medigap policy without being denied or charged more for pre-existing conditions. If you wait longer than 63 days, insurance companies can refuse to cover you or charge you a higher premium. You can also enroll in a Part D plan during the same window if you want prescription drug coverage.
Medicare Advantage vs. Original Medicare: the main differences
| Feature | Medicare Advantage | Original Medicare |
|---|---|---|
| Who pays your claims | Private insurance company | Federal government |
| Monthly premium | Often $0, plus Part B premium | Part B premium only (no plan premium) |
| Doctor network | Must use in-network providers | Any doctor who accepts Medicare |
| Copays and deductibles | Yes, varies by plan | 20% coinsurance after deductible |
| Prior approval needed | Often yes | Rarely |
| Prescription drug coverage | Usually included | Must enroll in separate Part D plan |
| Medigap compatible | No | Yes |
Frequently Asked Questions
If I enroll in Medicare Advantage, do I lose my Medicare benefits?
No. You remain enrolled in Medicare and keep your Medicare card. Your coverage is delivered through a private plan instead of the federal government, but you still have the same basic benefits—hospital care, doctor visits, and preventive services. You can return to Original Medicare at any time during the annual enrollment period.
Can I have both Original Medicare and Medicare Advantage at the same time?
No. You must choose one or the other. If you enroll in Medicare Advantage, your Original Medicare coverage stops. If you later switch back to Original Medicare, your Medicare Advantage coverage ends. You cannot hold both simultaneously.
What happens to my Medigap policy if I switch to Medicare Advantage?
Your Medigap policy becomes useless because Medicare Advantage does not work with Medigap. You should cancel it to stop paying the premium. If you later return to Original Medicare, you have 63 days to enroll in a new Medigap policy without penalty.
Do I still pay Medicare taxes if I have Medicare Advantage?
If you are still working, yes—you and your employer still pay Medicare payroll taxes. If you are retired, this does not explore. Your Medicare Advantage plan does not change your tax obligations.
Can my Medicare Advantage plan be cancelled or changed by the insurance company?
Insurance companies can discontinue plans or change benefits, but they must notify you at least 30 days in advance. If your plan is discontinued, Medicare sends you information about other plans available in your area. You can switch to a different plan during the open enrollment period.