The NPI (National Provider Identifier) number is a 10-digit numerical identifier that identifies an individual provider or a healthcare entity. An NPI number is shared with other providers, employers, health plans, and payers for billing purposes. CMS.gov’s Administrative Simplification provisions of the Health Insurance Portability and Accountability Act of 1996 (HIPAA) mandated the adoption of a standard, unique health identifier for each healthcare provider. The NPI fulfills this provision. Currently, all covered healthcare providers, all health plans, and healthcare clearinghouses must use NPI numbers in the administrative and financial transactions adopted under HIPAA.