The NPI is an Administrative Standard under the Health Insurance Portability and Accountability Act (HIPAA). An NPI is a unique identifier for covered health care providers that was established to improve the efficiency and efficacy of electronic health information transmission. NPIs must be used in administrative and financial transactions by covered health care providers, all health plans, and health care clearinghouses.
The HIPAA Administrative Simplification provisions required each health care provider to use a common, unique health identification. The NPI was established as this standard by the NPI lookup tool Final Rule, which was issued on January 23, 2004.
To assign these unique identifiers, CMS created the National Plan and Provider Enumeration System (NPPES). Visit the NPPES website for more information on how to apply for an NPI.
What is the NPI number?
An NPI is a 10-digit numeric identifier. It does not contain information about you, such as your practicing state, provider type, or specialty. Even if your name, address, taxonomy, or other information changes, your NPI will remain the same.
Providers must use the NPI instead of alternative provider identifiers such as Provider Transaction Access Number (PTAN), Quality Improvement Evaluation System (QIES), Certification and Survey Provider Enhanced Reporting (CASPER), and National Supplier Clearinghouse in HIPAA standard transactions.
NPIs can also be classified into two types. Type 1 is at the practitioner level; for example, all physicians and mid-level providers, such as Nurse Practitioners and Physician Assistants, will have their NPI in a group practice.

In addition, the group will be assigned a Type 2 NPI (or more depending on how the group chooses to enumerate). If a group wishes, it may have more than one NPI in specific conditions. A group with many offices or a lab, for example, can choose to get a Type 2 NPI for each office or ancillary.
Why do I need an NPI number?
The Administrative Simplification provisions of the Health Insurance Portability and Accountability Act of 1996 (HIPAA) required each healthcare provider to use a standard, unique health identifier, according to CMS.gov. This requirement is met by the NPI.
In the administrative and financial activities required by HIPAA, all covered healthcare providers, health plans, and healthcare clearinghouses must use NPI numbers. If you are a health care provider or any covered entity then youshould have an NPI number as mandated by HIPAA.