# NPI (National Provider Identifier) Key: `identity.medical.npi` 10-digit numeric identifier for US healthcare providers, issued by CMS. Includes a Luhn check digit as the 10th digit. Required for HIPAA transactions. Format: exactly 10 digits. NPIs are issued with a first digit of 1 or 2; the CMS check-digit document reserves other first digits for use coordinated with the standard health plan identifier. Page: Samples: `1234567893`, `1003000126`, `1992789457` ## Background ### Origin A final rule published in the Federal Register on January 23, 2004 adopted the National Provider Identifier (NPI) as the standard unique health identifier for health care providers.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) The rule was issued by the Centers for Medicare \& Medicaid Services, part of HHS.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) It implements some of the requirements of the Administrative Simplification subtitle F of the Health Insurance Portability and Accountability Act of 1996 (HIPAA).[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) Health care providers could apply for NPIs beginning on May 23, 2005.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) Covered entities other than small health plans had to use the NPI in standard transactions no later than May 23, 2007.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) Small health plans had until May 23, 2008.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) The May 7, 1998 proposed rule described the NPI as an 8-position alphanumeric identifier, with a numeric check digit in the 8th position.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) That format was proposed to keep the identifier as short as possible while providing an identifier pool that would serve the industry's needs for a long time.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) A strong majority of commenters recommended instead that the NPI be a 10-position numeric identifier.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) Commenters who preferred a numeric identifier said it is more quickly and accurately keyed in data-entry applications.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) The final rule made the NPI a 10-position numeric identifier, with the 10th position being an ISO standard check digit.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) CMS estimated that 200 million NPIs would last approximately 200 years.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) The rule says that if additional capacity is needed in the future, additional numeric digits will be added to the identifier.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) The NPI is an intelligence-free numeric identifier.[[2]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand) CMS reasoned that coded information about the provider in the identifier would mean issuing a new NPI any time that information changed.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) The USA Registration Committee approved the NPI as an International Standards Organization card issuer identifier in August 1996 for use on standard health identification cards.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) ### Use An NPI consists of 9 numeric digits followed by one numeric check digit.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) The check digit is calculated using the Luhn formula for computing the modulus 10 double-add-double check digit.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) When an NPI is used as a card issuer identifier on a standard health identification card, it is preceded by the prefix 80840.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) In that prefix, 80 indicates health applications and 840 indicates the United States.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) The check digit is always calculated as if the prefix is present.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) In CMS's worked example, the 9-position identifier 123456789 gives the NPI 1234567893.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) CMS's specification says NPIs will initially be issued with the first digit 1 or 2, to avoid collisions with other card issuer identifiers.[[3]](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) Treat a leading 1 or 2 as a description of the numbers issued so far rather than a rule that can never change. (Meridian's view) Under the rule, each health care provider may receive and use only one NPI.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) An NPI is inactivated upon death or dissolution of the health care provider.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) CMS notes that issuance of an NPI does not ensure or validate that the health care provider is licensed or credentialed.[[4]](https://download.cms.gov/nppes/NPI_Files.html) The NPI application form lets providers furnish other identifiers they hold, such as OSCAR, UPIN, DEA and Medicaid numbers.[[1]](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) Keep NPIs as text rather than integers, so the column keeps its fixed ten-digit width and nobody sums or averages it by accident. (Meridian's view) ### Where you'll meet it In September 2007, CMS began disclosing NPPES health care provider data that are disclosable under the Freedom of Information Act to the public.[[5]](https://www.cms.gov/medicare/regulations-guidance/administrative-simplification/data-dissemination) The NPI Registry is a query-only database, updated daily, that can be searched by NPI or provider name.[[5]](https://www.cms.gov/medicare/regulations-guidance/administrative-simplification/data-dissemination) CMS offers a Full Replacement Monthly NPI File, a Weekly Incremental NPI File and a Full Replacement NPI Deactivation File.[[5]](https://www.cms.gov/medicare/regulations-guidance/administrative-simplification/data-dissemination) CMS's Medicare Physician \& Other Practitioners - by Provider and Service data identifies the rendering provider on the claim by NPI, in the Rndrng\_NPI column.[[6]](https://data.cms.gov/sites/default/files/2025-03/bbb1e50e-5ba8-42ed-b072-18368b6f37f9/MUP_PHY_RY25_20250312_DD_PRV_SVC_508.pdf) ## Sources 1. [Federal Register, Volume 69 Issue 15 (Friday, January 23, 2004)](https://www.govinfo.gov/content/pkg/FR-2004-01-23/html/04-1149.htm) — standard 2. [National Provider Identifier Standard (NPI)](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand) — documentation 3. [Requirements for National Provider Identifier (NPI) and NPI Check Digit](https://www.cms.gov/Regulations-and-Guidance/Administrative-Simplification/NationalProvIdentStand/Downloads/NPIcheckdigit.pdf) — documentation 4. [NPI Files](https://download.cms.gov/nppes/NPI_Files.html) — dataset 5. [Data Dissemination \| CMS](https://www.cms.gov/medicare/regulations-guidance/administrative-simplification/data-dissemination) — organisation 6. [Medicare Physician \& Other Practitioners - by Provider and Service Data Dictionary](https://data.cms.gov/sites/default/files/2025-03/bbb1e50e-5ba8-42ed-b072-18368b6f37f9/MUP_PHY_RY25_20250312_DD_PRV_SVC_508.pdf) — dataset