On January 23, 2004, the Secretary of Health and Human Services published a Final Rule that adopted the National Provider Identifier (NPI). The NPI will be the standard identifier for covered health care providers to use in filing and processing health care claims and other transactions.

The Centers for Medicare and Medicaid Services (CMS) has developed the National Plan and Provider Enumeration System (NPPES) to assign these unique identifiers. The NPI is a numeric 10-digit identifier, consisting of nine numbers plus an ISO standard check-digit in the 10th position. It is accommodated in all standard transactions, and contains no embedded information about the health care provider that it identifies.

Providers required to obtain a NPI include physicians, non-physician healthcare practitioners, other suppliers and certified providers such as institutions and ancillary providers (i.e., home health agencies and skilled nursing facilities).