The National Provider Identifier (NPI) is a unique 10-digit number that identifies a healthcare provider in HIPAA standard transactions such as claims. CMS administers it through the National Plan and Provider Enumeration System (NPPES), and getting one is free. Any provider who bills Medicare, Medicaid, or most commercial insurers needs an NPI, and every claim must carry it.
There are two types. A Type 1 NPI belongs to an individual provider, such as a physician, nurse practitioner, or therapist. A Type 2 NPI belongs to an organization, such as a group practice, clinic, or billing entity. A provider who incorporates a practice may need both, and the choice of which to bill under is covered in group NPI or individual NPI.
An NPI is assigned once and stays with the provider for a career, across employers, locations, and specialty changes. The number carries no information about licenses or credentials. The NPPES record behind it, including the practice address and taxonomy code, must be kept current, and HIPAA requires changes to be reported within 30 days. Mismatched NPPES, CAQH, and enrollment data is a common cause of credentialing and claim delays.
You need an NPI before you can enroll with Medicare or credential with commercial payers. For the Medicare side, see How to Get Credentialed with Medicare.