William Tatomer, MD
NPI 1104862689 · Psychiatry Physician · San Mateo, CA
Enrolled with Medicare as Practitioner - Psychiatry · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Provider details
- NPI number
- 1104862689
- Entity type
- Individual
- Primary specialty
- Psychiatry PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- Yes
- License
- C35537 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
19 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
556 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) |
|---|---|---|
| Psychotherapy With Evaluation and Management Visit, 45 Minutes90836 | 278 | $97 |
| Established Patient Office Or Other Outpatient Visit With Straightforward Medical Decision Making, If Using Time, 10 Minutes Or More99212 | 278 | $66 |
Typical Medicare-allowed amounts for these services range $66–$97 (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 · 12 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Clonazepam | 54 |
| Escitalopram Oxalate | 49 |
| Sertraline Hcl | 40 |
| Fluoxetine Hcl | 25 |
| Trazodone Hcl | 21 |
| Lithium Carbonate | 17 |
| Quetiapine Fumarate | 17 |
| Aripiprazole | 16 |
| Dextroamphetamine/Amphetamine |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-06-21
- Last updated
- 2010-04-16
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.