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PECOS provider enrollment and ownership data
PECOS is Medicare's provider enrolment system. Its public extracts identify every enrolled provider and the parties associated with it. WhoOwnsCare uses it to establish which 16,019 providers exist, what type they are, and which legal entity holds each enrolment.
The enrolment identifier is the key to everything and the source of the subtlest error in this dataset.
Enrollment identifiers change, and that breaks joins
When a provider changes hands it is issued a new enrolment identifier. The old one is retired and disappears from the current enrolment file. A change-of-ownership record names the seller by that retired identifier.
Join the two naively and every divestiture in the dataset silently evaluates to zero — not an error, not a warning, just a permanent zero that looks like a finding. Sellers must be attributed by their own registered identity instead. We keep a regression test asserting that those identifiers remain unmatchable, precisely so the join can never quietly come back.
What PECOS does not tell you
- It does not group entities into companies.
- It does not distinguish an operator from a landlord.
- It reflects enrolment, not licensure — a facility can be certified but not yet enrolled, which is why provider counts differ slightly between CMS files.
How WhoOwnsCare uses it
PECOS establishes the provider universe and the legal entity behind each enrolment. The ownership files supply the relationships, Care Compare supplies operating measures, and cost reports supply financials. Each is loaded with its own vintage recorded, and a checksum of the exact file used.
Common questions
What is PECOS?
The Provider Enrollment, Chain and Ownership System — Medicare's enrolment database. Public extracts are published through CMS's open data portal.
Is PECOS the same as the nursing home ownership file?
No. PECOS establishes who is enrolled; the ownership files describe who is associated with them and in what role.