Matthew Williams, MD
NPI 1326626797 · Psychiatry Physician · San Francisco, CA
Enrolled with Medicare as Practitioner - Psychiatry · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Matthew Williams, MD is a Psychiatry Physician provider in San Francisco, CA (NPI 1326626797).
Provider details
- NPI number
- 1326626797
- Entity type
- Individual
- Primary specialty
- Psychiatry PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Student, Health Care
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
5 yrs in NPPES registry
- Profile completeness28% of score
83% of core fields populated
- Practice footprint17% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
168 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. 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.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 80 | $132 |
| Psychotherapy With Evaluation and Management Visit, 30 Minutes90833 | 73 | $70 |
| Psychiatric Diagnostic Evaluation With Medical Services90792 | 15 | $186 |
Typical Medicare-allowed amounts for these services range $70–$186 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 22 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Bupropion Hclbrand: Bupropion Xl | 98 | 14 |
| Duloxetine Hcl | 64 | — |
| Mirtazapine | 33 | — |
| Sertraline Hcl | 25 | — |
| Aripiprazole | 24 | — |
| Clonazepam | 22 | — |
| Trazodone Hcl |
Practice location
Mailing address
Additional practice locations (1)
- 1801 Vicente StSan Francisco, CA 94116-2923Phone: (415) 681-3211
Registry dates
- Enumerated
- 2021-03-29
- Last updated
- 2024-05-02
- Certified
- 2023-04-11
Frequently asked questions
- What is Matthew Williams's NPI number?
- Matthew Williams's National Provider Identifier (NPI) is 1326626797, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Matthew Williams's specialty?
- Matthew Williams is listed in the NPPES registry with a primary specialty of Psychiatry Physician (Allopathic & Osteopathic Physicians).
- Where is Matthew Williams located?
- Matthew Williams's practice location on file with NPPES is 401 Parnassus Ave, San Francisco, CA 94143-2211.
- What is Matthew Williams's phone number?
- The practice phone number listed in the NPPES registry for Matthew Williams is (415) 476-7527.
- Does Matthew Williams accept Medicare?
- Matthew Williams is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Matthew Williams's NPI active?
- Yes — Matthew Williams's NPI (1326626797) is active in the NPPES registry as of the last update on 2024-05-02.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.