What Is the NUCC Taxonomy? How Provider Specialties Are Classified

What the taxonomy code set is

The Health Care Provider Taxonomy Code Set is maintained by the National Uniform Claim Committee (NUCC), which took over its administration in 2001. NUCC describes it as an external, nonmedical code set designed for electronic health care transactions, including those mandated under HIPAA. Each code is a unique alphanumeric code, ten characters long, and NUCC notes that the codes define an area of specialty rather than the services a provider renders.

According to NUCC, the code set is used in HIPAA transactions and in the application for an NPI. Taxonomy codes are self-selected by the provider: NUCC says choosing the most appropriate code is a business decision each provider makes based on their education and training. CMS explains on its health care taxonomy page that a provider may select more than one code but must indicate one of them as primary.

The three levels of a code

Each code sits in a hierarchy with up to three levels:

1. Provider grouping: a broad group, such as "Allopathic & Osteopathic Physicians", "Physician Assistants & Advanced Practice Nursing Providers", "Dental Providers", "Hospitals" or "Ambulatory Health Care Facilities".
2. Classification: a field of practice within the group, such as Internal Medicine, Family Medicine, Nurse Practitioner or General Acute Care Hospital.
3. Area of specialization: a narrower focus within the classification, such as Cardiovascular Disease within Internal Medicine. Not every classification has one.

Examples

You can look up any code in the NUCC taxonomy look-up. A few common ones:

• 207R00000X: Allopathic & Osteopathic Physicians, Internal Medicine.
• 207RC0000X: Internal Medicine, Cardiovascular Disease.
• 207RI0011X: Internal Medicine, Interventional Cardiology.
• 208D00000X: Allopathic & Osteopathic Physicians, General Practice.
• 207Q00000X: Allopathic & Osteopathic Physicians, Family Medicine.
• 363L00000X: Nurse Practitioner.
• 363A00000X: Physician Assistant.
• 282N00000X: General Acute Care Hospital.
• 261Q00000X: Clinic/Center.

The code itself is just a label. What matters is the grouping, classification and specialization it stands for, and the definition NUCC publishes with each code.

How the code set changes

NUCC explains in its publication FAQ that the code set is released twice a year, in January and July. The January release takes effect on April 1 and the July release on October 1. New versions can add codes, change definitions or retire codes that are no longer used. A provider whose code is retired or no longer fits needs to choose a new one in NPPES, and directories that load the new version may show updated specialty names for the same code.

Primary and secondary taxonomy codes

A provider can list more than one taxonomy code. The public NPPES downloadable file has room for up to 15 codes per NPI, each with an optional license number and license state, and a switch that marks one code as primary.

The primary code is the one the provider considers their main type of practice. For example, a cardiologist might list Internal Medicine and Cardiovascular Disease and mark Cardiovascular Disease as primary. An organization such as a multi-specialty clinic may list several facility and clinic codes.

What a secondary code can mean

Secondary codes can reflect a second field of practice, an earlier specialty or a broader classification. They can also be left over from an older version of the record. Because providers choose and update codes themselves, a secondary code is a hint, not evidence of current practice in that field.

What a taxonomy code does not tell you

NUCC is direct about this in its FAQ on licensure and certification: selecting a taxonomy code does not replace any credentialing or validation process, and a code that mentions a certifying board in its definition does not imply that the provider met that board's requirements. NUCC also states that scope of licensure is not within the purview of the code set. In practice this means:

• No check of training. Selecting "Cardiovascular Disease" does not mean anyone confirmed that the provider finished a cardiology fellowship.
• Board certification is not included. Board certification is granted by specialty boards, not by NUCC or NPPES. For physicians certified by an ABMS member board, Certification Matters shows the current status.
• The license number is self-reported. A license number next to a taxonomy code is what the provider entered. The state board decides whether that license is active.
• No scope-of-practice decision. What a provider may legally do is set by state law and their license, not by the code.

Taxonomy codes and Medicare specialties

When a clinician enrolls in Medicare, they report a Medicare specialty, which uses CMS's own specialty codes rather than NUCC codes. CMS publishes the Medicare Provider and Supplier Taxonomy Crosswalk to show which taxonomy codes correspond to each Medicare specialty. The two do not always line up one to one, so the same clinician can show a slightly different specialty name in Medicare data than in NPPES.

T-MedInfo specialty pages and profiles use the NPPES taxonomy codes, not the Medicare specialty. If a Medicare tool such as Care Compare shows a different specialty name for the same clinician, this crosswalk is usually the reason.

How T-MedInfo uses taxonomy codes

Specialty pages on this site, such as "Internal Medicine in a city", are built from NPPES taxonomy codes. A clinician is listed under the specialty of their primary code. If the primary code describes a facility rather than a clinical field, we use the next clinical code in the record; a clinician with no clinical code is shown as general practice.

A profile lists every taxonomy code in the NPPES record with its specialty name and NUCC definition, and marks the primary one. License numbers appear exactly as reported, together with a link to the state board lookup.

Because the listing follows the provider's own choice of primary code, a clinician may appear under a broader specialty than you expect. A cardiologist who kept Internal Medicine as primary will be listed under Internal Medicine. It is worth reading the full list of codes on a profile, not just the page it appears on.

Using taxonomy codes when you look for care

• Use the classification and specialization to narrow a search, then confirm with the office what conditions the provider treats.
• If you need a specific kind of specialist, ask about training and board certification directly. Those facts are not in the code.
• If your health plan requires a referral, the plan decides which provider types count as specialists, not the taxonomy code.
• For the full picture of what an NPI record contains, see our NPI lookup guide.