Allergy/Immunology: Medicare enrollment by state

Taxonomy codes for allergy/immunology

CMS's crosswalk maps 3 NUCC taxonomy codes to Medicare specialty 03. A provider enrolling as allergy/immunology should hold one of them as the primary taxonomy on their NPI.

Where it is concentrated

Raw counts follow population, so the more telling figure is each state's share: what fraction of the state's Medicare-enrolled NPIs are allergy/immunology. Nationally the specialty is 0.2% of enrolled NPIs. The highest shares are in California (0.2%), New York (0.2%), Texas (0.2%); the lowest in Vermont (0%), Wyoming (0.1%), North Dakota (0.1%). 51 of the 51 (50 states and DC) have at least one enrolled.

Billing versus order-and-refer enrollment

Medicare enrolls practitioners in two ways. A full enrollment lets the provider bill Medicare for their own services; it is what the 4,224 above count. An order-and-refer-only enrollment lets a provider who never bills Medicare — a resident, a VA or military physician, a dentist ordering imaging — still order tests, equipment and referrals that Medicare pays for. 119 allergy/immunology NPIs hold that limited enrollment.

Every state

Counts are unique NPIs enrolled in each state; a provider enrolled in two states counts in both. The share is of all Medicare-enrolled NPIs in that state.

Sources: CMS Medicare Fee-For-Service Public Provider Enrollment, extract of 2026-09-29; CMS Medicare Provider and Supplier Taxonomy Crosswalk, August 2026. Checked 2026-10-24. Methodology.