William Day, M.D.
NPI 1740745041 · Allergy & Immunology Physician · Portsmouth, VA
Enrolled with Medicare as Order and Referring Only - Allergy/Immunology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Day, M.D. is a Allergy & Immunology Physician provider in Portsmouth, VA (NPI 1740745041).
Provider details
- NPI number
- 1740745041
- Entity type
- Individual
- Primary specialty
- Allergy & Immunology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- Yes
- License
- 0101271195 (VA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure33% of score
7 yrs in NPPES registry
- Profile completeness33% of score
100% of core fields populated
- Practice footprint20% of score
2 documented practice locations
- Open Payments transparency13% of score
Has Open Payments disclosures (2024)
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$51 across 2 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Additional practice locations (1)
- 8901 Rockville PikeBethesda, MD 20889-0001Phone: (757) 953-5000
Registry dates
- Enumerated
- 2019-01-31
- Last updated
- 2025-06-18
- Certified
- 2025-06-18
Frequently asked questions
- What is William Day's NPI number?
- William Day's National Provider Identifier (NPI) is 1740745041, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Day's specialty?
- William Day is listed in the NPPES registry with a primary specialty of Allergy & Immunology Physician (Allopathic & Osteopathic Physicians).
- Where is William Day located?
- William Day's practice location on file with NPPES is 620 John Paul Jones Cir Ste 275, Portsmouth, VA 23708-2197.
- What is William Day's phone number?
- The practice phone number listed in the NPPES registry for William Day is (757) 953-2000.
- Does William Day accept Medicare?
- William Day is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Day's NPI active?
- Yes — William Day's NPI (1740745041) is active in the NPPES registry as of the last update on 2025-06-18.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.