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CMS MSSP ACOCMS Medicare Shared Savings Program ACO Participants
Centers for Medicare & Medicaid Services (CMS) · Tier-2 · profile-enrichment (renders on matched profiles)
The CMS Medicare Shared Savings Program (MSSP) publishes the Accountable Care Organization Participants file, identifying the legal business names participating in each ACO by performance year. As of the 2026-06-14 snapshot, Fonteum holds 15,329 participant records.
How this source shows up on Fonteum.
Surfaces ACO id, participant legal business name, and performance year on the dataset page and via the read API. The public CMS file carries no participant TIN or NPI (those are restricted to ResDAC), so entity-graph linkage is name-keyed and deferred — ambiguous matches are held.
What this source does NOT mean
MSSP participation is a value-based-care program enrollment record — it does not indicate provider quality, shared-savings performance, outcomes, or endorsement. The public file lists who participates, not how an ACO performed.
Research and data questions this source supports.
- List the legal business names participating in each Medicare Shared Savings Program ACO by performance year.
- Track ACO participant composition over time across performance years.
- Build a research dataset of MSSP participation with row-level provenance and snapshot dates.
- Combine MSSP participation with PECOS enrollment and QPP MIPS signals for value-based-care analysis.
Dataset size: 15,329 ACO participant records (2026-06-14 snapshot)
Per-field display contract.
Fields listed below show their configured `display_allowed` flag from the §94 provenance schema. Fields marked write-locked are captured for audit and are not rendered on profile pages.
Research-only — never on profiles
3 fieldsWhat we can’t infer from this source.
- The public CMS file carries no participant TIN or NPI (restricted to ResDAC); entity-graph linkage is name-keyed and deferred.
- Participation is recorded per performance year — a participant may appear across multiple years.
- MSSP participation is a program-enrollment fact, not a measure of shared-savings performance or quality.
Authority, license, publisher cadence.
Authority
Centers for Medicare & Medicaid Services (CMS)
Tier
Tier-2 · profile-enrichment (renders on matched profiles)
Publisher / configured cadence
Declared or configured cadence: Annual — CMS publishes one Accountable Care Organization Participants file per performance year. Not evidence of the latest loaded source date.
License
U.S. government public-domain data. Free to use with attribution. License ↗
Official URL
Attribution requirement
Source: Centers for Medicare & Medicaid Services (CMS), Medicare Shared Savings Program · Performance year {YYYY}
What the source allows.
U.S. government public-domain works. CMS publishes the ACO Participants file at data.cms.gov; attribution to CMS / the Medicare Shared Savings Program is the only requirement.
Official API, bulk download, and Fonteum endpoints.
Official API / download
Fonteum surface
Common questions about CMS MSSP ACO.
- What is the Medicare Shared Savings Program?
- The Medicare Shared Savings Program (MSSP) is CMS's largest accountable care program. Accountable Care Organizations (ACOs) — groups of providers that coordinate care for Medicare beneficiaries — can share in savings they generate against a spending benchmark. CMS publishes the list of participating organizations each performance year.
- What does the ACO Participants file contain?
- The public CMS Accountable Care Organization Participants file lists each ACO's id and the legal business names of its participants, by performance year. As of the 2026-06-14 snapshot, Fonteum holds 15,329 participant records.
- Does the public file include participant NPIs or TINs?
- No. The public CMS file carries no participant TIN or NPI — those identifiers are restricted to ResDAC under a data-use agreement. Fonteum's entity-graph linkage is therefore name-keyed and deferred; ambiguous matches are held rather than asserted.
- Does MSSP participation indicate ACO performance?
- No. The Participants file records who participates in an ACO, not how the ACO performed. Shared-savings results are published separately. MSSP participation is a program-enrollment fact, not a measurement of quality or savings performance.
- How fresh is the data?
- CMS publishes one ACO Participants file per performance year. Loaded dates must be read from the specific response; publisher cadence is not proof of a completed load, and record-level provenance values can be null.
Where this source already shows up.
Related sources in the graph
- /sources → The generated source-catalog subset — documented datasets Fonteum cites.
- /data-provenance → The provider graph — pipeline diagram, source-family clusters, field-level provenance examples, display rules.
- /methodology → Documented sourcing, publisher cadence, observed freshness, and corrections policy.
- /editorial-policy → Independence, sourcing, conflicts, corrections, retractions.