Referring provider
A referring provider is not the rendering provider and not the billing organization. Each role can be a different NPI.
Source: CMS, Ordering and Referring. Page read October 14, 2026.
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Definition · Provider identifiers and enrollment
Referring provider
The referring provider is the physician or practitioner who referred the patient for the service on a claim. Medicare asks for that NPI on many claims, and the NPI has to be eligible to order and refer. The public opt-out file carries that flag. The opt-out lookup is at /medicare-opt-out-lookup.
Questions
Referring provider, answered
Where do I check the ordering flag?
The public CMS ordering file and the opt-out row both carry an eligible-to-order field. Read the field. Do not infer it from the NPI alone.