The NPI (National Provider Identifier) code that identifies the facility to which the patient was referred for further care.

NPI, a unique identification number for US health care providers, was scheduled for 2007-2008 implementation by the Centers for Medicare & Medicaid Services (CMS) as part of the Health Insurance Portability and Accountability Act of 1996 (HIPAA). For billing purposes, large practices and large group providers were required to use NPI codes by May 2007; small health plans were required to use NPI codes by May 2008.

This number is used to document and monitor referral patterns.

Codes [only valid NPI assigned 10-digit numeric codes (9-digit number plus 1 check digit). The check digit algorithm is available at: https://nppes.cms.hhs.gov/NPPES/NPIRegistryHome.do]