What Is an NPI Number?
A National Provider Identifier (NPI) is a unique, 10-digit number assigned to healthcare providers in the United States. It is the standard identifier used in HIPAA electronic transactions — claims, eligibility checks, referrals, and more — and is issued by the Centers for Medicare & Medicaid Services (CMS) through the NPPES registry.
Last updated June 10, 2026
What the NPI replaced
Before the NPI, providers juggled a different identifier for nearly every health plan they billed — a Medicare number here, a Medicaid number there, separate payer-assigned IDs everywhere else. The NPI was created under HIPAA (the Administrative Simplification provisions) to replace that tangle with a single, plan-independent number that follows the provider across payers and over time.
The number itself is intelligence-free: it carries no information about the provider's specialty, state, or type. Everything descriptive — name, taxonomy, practice address — lives in the public NPPES record attached to the number.
Who needs an NPI?
- Individual providers (Type 1) — physicians, nurse practitioners, dentists, therapists, pharmacists, and other clinicians who are HIPAA-covered.
- Organizations (Type 2) — hospitals, group practices, clinics, pharmacies, labs, and other provider entities.
- Any provider who transmits health information electronically in connection with a HIPAA transaction is required to obtain and use an NPI.
How an NPI is structured
An NPI is exactly 10 digits. The first nine identify the provider; the tenth is a check digit computed with the Luhn algorithm (using an `80840` prefix for the health-industry namespace). That check digit lets systems catch most typos instantly without a database lookup.
Paste any 10-digit number into our free validator to confirm the Luhn check digit is correct — no data leaves your device.
Open the NPI validatorWhere the data is public
NPPES data (other than certain restricted fields) is published by CMS as a public-domain file and through the NPI Registry. That is exactly what powers the search on this site — you can look up any active provider by name, NPI, specialty, or location.
Frequently asked questions
No. An NPI is a single identifier used across all payers. A Medicare PTAN (or legacy Medicare number) is a separate, Medicare-specific enrollment identifier that is linked to — but distinct from — the NPI.
Generally no. An NPI is intended to be permanent and stays with the provider for life, even if they change names, specialties, or locations. It can be deactivated (for example, on death or dissolution of an organization).
Yes. CMS publishes NPPES data as a public-domain dataset and through the NPI Registry. Sensitive fields are withheld, but names, NPIs, taxonomies, and practice locations are public.