Example result
NPI number 1154392231, looked up in the NPPES NPI Registry.
- Type
- Organization (NPI-2)
- Organization name
- Mayo Clinic Arizona
- Registry status
- Active
- Primary specialty
- General Acute Care Hospital, taxonomy code 282N00000X
- Practice address
- 5777 E Mayo Blvd, Phoenix, AZ 85054-4502
- Practice phone
- 480-342-2000
- Enumerated
- January 27, 2006
- Last updated
- April 16, 2026
- Source
- CMS NPPES NPI Registry, API version 2.1
Captured 2026-10-19.
How it works
- Type the 10-digit NPI number. Spaces and dashes are fine.
- The page checks the last digit against the other nine first, so a typo shows up at once. A well-formed number is then looked up in the NPPES NPI Registry, which needs no key and no account.
- The page lists the public facts the record holds and leaves out everything else. It also tells you plainly what an NPI does and does not prove.
What an NPI is
The National Provider Identifier is a 10-digit number that identifies a health care provider in the United States. Individual providers such as physicians, nurses and dentists get an NPI-1. Organizations such as hospitals, clinics, pharmacies and laboratories get an NPI-2. The number carries no meaning in its digits. The last digit is a check digit computed from the first nine, which is how this page catches a mistyped number before it asks the registry.
CMS publishes the registry as a free public directory of active NPI records and updates it daily. The registry API returns the record as the provider reported it.
What a match does and does not tell you
A match shows that the number is issued and active, and shows what the provider reported about itself. CMS notes that holding an NPI is no proof that the provider is licensed or credentialed. To check a license, use the licensing board of the state in the record.
The data is self-reported. Providers are responsible for keeping their own record current, so a specialty, address or phone number can be out of date. The last-updated date on the page tells you when the provider last changed or certified the record.
The registry lists active NPIs. A number that was deactivated, or that was never issued, shows as not found in the registry, which is different from a number with a typo.
What this page leaves out
For individual providers the page shows only the practice location. The mailing address in the registry is often a home address, so it is never read onto this page. Fax numbers, license numbers, other identifiers, authorized official names and data exchange endpoints are also left out.
The page looks up one number at a time and shows the primary specialty only. It does not search by name and does not list every location a provider has.
NPI registry fields in plain words, from the NPPES API help and the CMS data dissemination page
| Registry field | Value | Plain meaning |
|---|---|---|
| enumeration_type | NPI-1 | An individual health care provider, such as a physician, nurse, dentist or pharmacist. |
| enumeration_type | NPI-2 | An organization that provides health care, such as a hospital, clinic, pharmacy or laboratory. |
| basic.status | A | The NPI is active. The registry lists active numbers only. |
| taxonomies (primary) | Code such as 282N00000X | The provider type and specialty the provider marked as primary. The code comes from the Health Care Provider Taxonomy code set, and the registry gives a readable description beside it. |
| addresses (LOCATION) | Street, city, state, ZIP, phone | The practice location the provider listed. This is the only address the page shows. |
| basic.enumeration_date | A date | The date the NPI was first issued. |
| basic.last_updated | A date | The date the provider last changed or certified the record. |
| NPI check digit | Last digit | A Luhn check digit computed over the number with the prefix 80840 in front. A number that fails it cannot have been issued. |
Sources
- NPPES NPI Registry API help page (fields, limits and notes) read 2026-10-19
- CMS NPPES data dissemination page (what the registry discloses and how often it updates) read 2026-10-19
This tool is run by LookValid. It is not connected to any agency, company or service named on this page.
Frequently asked questions
Does an NPI prove a provider is licensed?
No. CMS says that being issued an NPI is no proof that the provider is licensed or credentialed. An NPI shows that the provider registered for the number. Check the license with the state licensing board.
What is the difference between NPI-1 and NPI-2?
NPI-1 belongs to an individual health care provider. NPI-2 belongs to an organization, such as a hospital, clinic, pharmacy or laboratory. A group practice can hold an NPI-2 while each of its clinicians holds an NPI-1.
Why does the page say a number was not found in the registry?
The registry has no live entry under that number. The number may have been deactivated, may never have been issued. The page calls a number invalid only when it is malformed or its last digit fails the check, never because the registry has no record.
Why does the page say the registry did not answer?
The CMS registry did not respond in time or answered with an error. That says nothing about the number, so the page does not call it missing. Try again in a moment.
Can I trust the specialty and address?
They are what the provider reported, and the provider is responsible for keeping them current. Read the last-updated date. For a decision that matters, confirm the details with the practice.
Why is the mailing address not shown?
For an individual the mailing address is often a home address. The page shows the practice location only, which is the address the provider lists for seeing patients.