Margaret Mass, MD
NPI 1083343107 · Family Medicine Physician · Seattle, WA
Enrolled with Medicare as Practitioner - Family Practice · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Margaret Mass, MD is a Family Medicine Physician provider in Seattle, WA (NPI 1083343107).
Provider details
- NPI number
- 1083343107
- Entity type
- Individual
- Primary specialty
- Family Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- No
- License
- MD70026676 (WA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure33% of score
4 yrs in NPPES registry
- Profile completeness33% of score
100% of core fields populated
- Practice footprint20% of score
3 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.
$66 across 3 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 (2)
- 3901 Hoyt AveEverett, WA 98201-4918Phone: (425) 303-3091
- 509 Olive WaySeattle, WA 98101-1720Phone: (206) 329-1760
Registry dates
- Enumerated
- 2022-06-06
- Last updated
- 2026-01-27
- Certified
- 2026-01-27
Frequently asked questions
- What is Margaret Mass's NPI number?
- Margaret Mass's National Provider Identifier (NPI) is 1083343107, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Margaret Mass's specialty?
- Margaret Mass is listed in the NPPES registry with a primary specialty of Family Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Margaret Mass located?
- Margaret Mass's practice location on file with NPPES is 904 7th Ave, Seattle, WA 98104-1132.
- What is Margaret Mass's phone number?
- The practice phone number listed in the NPPES registry for Margaret Mass is (206) 860-4700.
- Does Margaret Mass accept Medicare?
- Margaret Mass is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Margaret Mass's NPI active?
- Yes — Margaret Mass's NPI (1083343107) is active in the NPPES registry as of the last update on 2026-01-27.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.