DR. WILLIAM GRANT DAY M.D.
NPI 1740745041
Allergy & Immunology in Portsmouth, VA

Q: What is William Day's NPI number?

The NPI number for William Day is 1740745041. It was assigned to this individual provider in the NPPES registry on January 31, 2019.

Q: What is William Day's specialty?

The primary specialty registered for this NPI is Allergy & Immunology with taxonomy code 207K00000X.

Q: When was this NPI record last updated?

The NPPES record for William Day was last updated on June 30, 2026. NPI Profile syncs with the weekly NPPES data releases published by CMS.

Active since January 31, 2019PECOS Enrolled

620 JOHN PAUL JONES CIR STE 275, PORTSMOUTH, VA 23708(757) 953-2000 Get Directions Write a Review

NPPES record last updated: June 30, 2026. Verified against the NPPES registry weekly; last sync: July 26, 2026.

Record update history: Jun 18, 2025, Jul 24, 2024, Jun 9, 2023 and 2 more (5 updates tracked since 2019).

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About Dr. William Grant Day M.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DR. WILLIAM GRANT DAY M.D. (NPI 1740745041) is an individual allergy & immunology provider in Portsmouth, Virginia, licensed in Virginia (0101271195) and active in the NPI registry since January 2019. He is enrolled in Medicare PECOS.

NPPES Registry Identity

NPI1740745041

Entity TypeIndividualMale

Primary Taxonomy207K00000X

Provider Legal NameDR. WILLIAM GRANT DAYCredential: M.D.

Location Address620 JOHN PAUL JONES CIR STE 275Portsmouth, VA 23708-2197

Mailing Address620 John Paul Jones CirPortsmouth, VA 23708-2111 · (757) 953-2194

Phone(757) 953-2000

Sole ProprietorYes

Enumeration DateJanuary 31, 2019

Last NPPES UpdateJune 30, 20265 updates tracked since enumeration

NPPES CertifiedJune 30, 2026

✔ NPI 1740745041 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses 2

★ Primary SpecialtyAllergy & ImmunologyAllopathic & Osteopathic Physicians

Taxonomy Code207K00000X

License✔ Licensed in VA · 0101271195

Definition

An allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Selected examples of such conditions include asthma, anaphylaxis, rhinitis, eczema, and adverse reactions to drugs, foods, and insect stings as well as immune deficiency diseases (both acquired and congenital), defects in host defense, and problems related to autoimmune disease, organ transplantation, or malignancies of the immune system.

Also ListedInternal MedicineTaxonomy 207R00000X · License 0101271195 (VA)

620 JOHN PAUL JONES CIR STE 275, Portsmouth, VA 23708

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Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, and ordering and referring status from the CMS PECOS system.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Dr. William Grant Day M.d. is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

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