Medicare Advantage

Medicare Advantage (Part C) plans are private plans that replace Original Medicare for enrolled beneficiaries. They must cover what Original Medicare covers, but they operate their own networks, their own prior authorization requirements, and their own appeal processes — which means for billing purposes an MA plan behaves far more like a commercial payer than like Medicare. Payer content ages fastest of anything on this site. Portals move, forms change, payer IDs get reassigned, and timely filing limits are contract-specific regardless of what any table says. Treat this page as orientation; the payer’s own current documentation and your executed contract are authoritative. Checked August 2026.

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MA versus Medicare FFS

Two errors practices make constantly:

1. Assuming Medicare enrollment covers MA. It does not. Each MA plan requires its own contract and credentialing.
2. Assuming Medicare’s 12-month filing limit applies. It does not. MA filing limits are contractual and frequently far shorter. Record each plan’s limit from your contract.

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The major MA plans

Humana, UnitedHealthcare, Aetna, Elevance/Anthem, Centene (Wellcare), Kaiser, and a large number of regional and provider-sponsored plans. Market share varies enormously by county.

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Enrollment

Per plan, generally requiring Medicare enrollment as a prerequisite plus a plan-specific contract and credentialing. Most pull from CAQH.

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Prior authorization

MA plans use prior authorization far more heavily than Medicare FFS. This is the operational difference most practices feel first.

• Build a per-plan auth-required list into scheduling
• Track authorized units against delivered units
• Use peer-to-peer review when authorization is denied

See Get prior authorizations.

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Appeals

The plan’s internal reconsideration, then the federal Medicare Advantage appeals process — which involves an independent review entity and further levels. The track differs from both commercial appeals and Medicare FFS appeals.

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Risk adjustment

MA plans are paid risk-adjusted capitated amounts by CMS based on enrollee diagnoses. Consequences for practices:

• Documentation and diagnosis coding specificity matter more to MA plans than to commercial payers
• Plans may run chart review programs and request records
• Some groups enter risk-sharing arrangements with MA plans — see Medical groups for why those complicate the MSO-PC structure

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Quirks worth knowing

• D-SNPs (dual eligible special needs plans) involve both Medicare and Medicaid rules
• Network adequacy varies by county; panels can be closed
• Rates are typically benchmarked to Medicare but negotiated