> ## Documentation Index
> Fetch the complete documentation index at: https://mso.getlemma.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Medicare Advantage

> How MA differs from Medicare fee-for-service for billing, authorization, timely filing, and appeals.

**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.**

## MA versus Medicare FFS

|                         | Medicare FFS                 | Medicare Advantage                                                   |
| ----------------------- | ---------------------------- | -------------------------------------------------------------------- |
| **Who pays**            | CMS, via MACs                | The MA plan                                                          |
| **Network**             | Any enrolled provider        | **The plan's network**                                               |
| **Enrollment**          | PECOS                        | **Contract with each MA plan**                                       |
| **Prior authorization** | Limited                      | **Extensive**                                                        |
| **Timely filing**       | 12 months, fixed             | **Contractual — often much shorter**                                 |
| **Appeals**             | The five-level federal track | The plan's process, then the federal MA track                        |
| **Coverage policy**     | NCDs and your MAC's LCDs     | Plan policy, which must cover at least what Original Medicare covers |

**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.

## 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.

## Enrollment

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

## 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](/guides/billing/get-prior-authorizations).

## 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.

## 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](/concepts/industries/medical-groups) for why those complicate the MSO-PC structure

## 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


## Related topics

- [The US payer landscape](/concepts/payments/the-payer-landscape.md)
- [Payers vs insurance companies (they're not synonyms)](/concepts/payments/payers-vs-insurance-companies.md)
- [Enroll and contract with commercial payers](/guides/enrollment/enroll-with-commercial-payers.md)
- [Set up EDI, ERA, and EFT with each payer](/guides/enrollment/set-up-edi-era-eft.md)
- [File appeals](/guides/billing/file-appeals.md)
- [How to use the payer reference](/reference/payers/overview.md)
- [Payer enrollment & submission links](/reference/payers/enrollment-links.md)
- [Timely filing limits by payer](/reference/payers/timely-filing-limits.md)