William Tsai, D.O.
NPI 1285620443 · Family Medicine Physician · Upland, CA
Enrolled with Medicare as Practitioner - Family Practice · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Tsai, D.O. is a Family Medicine Physician provider in Upland, CA (NPI 1285620443).
Provider details
- NPI number
- 1285620443
- Entity type
- Individual
- Primary specialty
- Family Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- D.O.
- Sex
- Male
- Sole proprietor
- No
- License
- 20A7115 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
20 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
634 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
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 .
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) |
|---|---|---|
| Advance Care Planning, First 30 Minutes99497 | 207 | $76 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 164 | $92 |
| Subsequent Nursing Facility Care With Straightforward Level of Medical Decision Making, Per Day, If Using Time, 20 Minutes Or More99308 | 155 | $76 |
| Telephone Medical Discussion With Physician, 11-20 Minutes99442 | 44 | $93 |
| Initial Nursing Facility Care With High Level of Medical Decision Making, Per Day, If Using Time, 50 Minutes Or More99306 | 21 | $148 |
| Annual Wellness Visit, Includes a Personalized Prevention Plan of Service (pps), Subsequent VisitG0439 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 162 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 805 | 203 |
| Amlodipine Besylate | 533 | 134 |
| Levothyroxine Sodium | 391 | 78 |
| Losartan Potassium | 367 | 100 |
| Metformin Hcl | 288 | 82 |
| Trazodone Hcl | 234 | 48 |
| Rosuvastatin Calcium |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$1,291 across 52 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
Registry dates
- Enumerated
- 2005-09-23
- Last updated
- 2024-04-24
- Certified
- 2024-04-24
Frequently asked questions
- What is William Tsai's NPI number?
- William Tsai's National Provider Identifier (NPI) is 1285620443, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Tsai's specialty?
- William Tsai is listed in the NPPES registry with a primary specialty of Family Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is William Tsai located?
- William Tsai's practice location on file with NPPES is 510 N 13th Ave Ste 101, Upland, CA 91786-4973.
- What is William Tsai's phone number?
- The practice phone number listed in the NPPES registry for William Tsai is (909) 985-8838.
- Does William Tsai accept Medicare?
- William Tsai is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Tsai's NPI active?
- Yes — William Tsai's NPI (1285620443) is active in the NPPES registry as of the last update on 2024-04-24.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.