Medicare Part C (Medicare Advantage)
Medicare Part C, or Medicare Advantage, is Medicare coverage delivered through a private plan that CMS pays a capitated rate to administer. MA plans must cover everything Original Medicare Parts A and B cover, usually bundle Part D drugs, and add benefits, but they impose networks and prior authorization that Original Medicare does not.
- Also called
- Medicare Advantage (MA)
- Minimum coverage
- At least Original Medicare Parts A & B
- Payment to plan
- Capitated per-member rate from CMS
- Common friction
- Networks and prior authorization
What is Medicare Advantage (Part C)?
Medicare Advantage is Original Medicare delivered through a private plan. CMS contracts with insurers and pays them a capitated monthly amount per enrollee; in exchange, the plan administers the member's Part A and Part B benefits and takes on the risk. Most MA plans bundle in Part D drug coverage and add benefits Original Medicare lacks, such as dental, vision, hearing, and fitness.
Structurally these are usually HMOs or PPOs, which means the network and referral rules of commercial managed care now sit on top of Medicare benefits.
How does Advantage differ from Original Medicare?
| Feature | Original Medicare | Medicare Advantage |
|---|---|---|
| Payer of claims | Medicare (MAC) | The private MA plan |
| Networks | Any provider accepting Medicare | Plan network (HMO/PPO) |
| Prior authorization | Rare | Common |
| Drug coverage | Separate Part D | Usually bundled |
| Medigap allowed | Yes | No |
The key operational point for billers: a Medicare Advantage patient is a commercial-style payer relationship, not a Medicare fee-for-service one.
How do you bill a Medicare Advantage plan?
Claims go to the MA plan, using its payer ID, not to the Medicare Administrative Contractor. Verify eligibility and network status before the visit, because an out-of-network HMO claim can deny in full. Contracted rates, timely filing windows, and appeal processes follow the plan's rules, which often differ from Original Medicare.
- Confirm the exact MA plan name and payer ID at check-in, not just "Medicare."
- Verify in-network status and any referral requirement.
- Check whether the service needs prior authorization.
- File to the plan within the plan's timely filing window.
Why do MA plans deny for authorization?
Example: a patient with an MA HMO gets an MRI ordered same-day. Original Medicare would pay it; the MA plan requires prior authorization and denies the claim because none was obtained. The service was medically necessary, but the plan's utilization-management rule was not followed.
Frequently asked questions
No. Medicare Advantage (Part C) is Medicare benefits administered by a private plan under contract with CMS. It must cover at least what Original Medicare Parts A and B cover, and usually adds Part D drugs plus extras like dental or vision. Unlike Original Medicare, MA plans use provider networks and prior authorization.
Because CMS pays the MA plan a capitated rate to take on the enrollee. The plan becomes the payer of record, so claims, appeals, and authorizations route to the plan, not to the Medicare Administrative Contractor. Billers must verify the specific MA plan and its payer ID, not just that the patient has Medicare.
No. Medigap supplements only work with Original Medicare. If a patient enrolls in a Medicare Advantage plan, a Medigap policy cannot pay toward MA cost sharing, and it is generally illegal to sell one to an MA enrollee. Patients often confuse the two, so verify which product they actually hold.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
Stop losing revenue to problems like this.
A free billing audit shows exactly where your practice is leaking money — no cost, no commitment.
