DR. WILLIAM TSAI (D.O.) – Family Medicine Physician, NPI 1285620443
Family Medicine Physician
Main info
Doctor Profile
Profile Insights
NPPES metrics only — not quality of care.
13,194 FAMILY PRACTICE in CA
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Provider Addresses for DR. WILLIAM TSAI (D.O.)
4950, San Bernardino Street, Montclair, San Bernardino County, California, 91763, United States
#218
MONTCLAIR, CA 917632328
Phone: (909) 398-0188
Fax: (909) 398-0187
Type: Mailing
510 N 13TH AVE STE 101
UPLAND, CA 917864973
Phone: (909) 985-8838
Fax: (909) 398-0187
Type: Mailing
NPPES updates history
No NPPES updates recorded for this provider.
Prescription Activity
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Open Payments (CMS)
CMS reports 79 Open Payments records for all available years, with a total value of $1,932.
Total Amount is formed as General ($1,932) + Research ($0) + Ownership ($0) = $1,932.
Last reported payment date: 2024-12-23 • Largest payer in this snapshot: Lilly USA, LLC ($264).
Total Amount
$1,932
General + Research + Ownership
Payments
79
Total payment records
General Amount
$1,932
General payments
Research Amount
$0
Research funding
Ownership Amount
$0
Ownership interests
Ownership Count
0
Ownership records
Last Payment Date
2024-12-23
Latest reported date
Top Companies
Largest payers in this snapshot
| Company | Amount |
|---|---|
| Lilly USA, LLC | $264 |
| Novartis Pharmaceuticals Corporation | $256 |
| Inari Medical, Inc. | $177 |
| PFIZER INC. | $106 |
| Teva Pharmaceuticals USA, Inc. | $100 |
Medicare Enrollment & Revalidation
Source: CMS public data · Not endorsed by CMS ·
Educational use only—not medical, billing, or legal advice.
PECOS enrollment status
Participating (accepts Medicare assignment)
Enrollment effective: 2003-12-30
PECOS data refreshed: 2026-05-27
Medicare revalidation (CMS due date list)
Due date not assigned yet
CMS is tracking this Medicare enrollment for revalidation, but has not published a due date.
Enrollment records
1
Earliest due date
Not assigned (TBD)
CMS data updated
2026-06-01
Revalidation progress
- Medicare enrolled
- On CMS revalidation list
- Due date assigned
- Revalidate in PECOS
CMS enrollment records
| Enrollment ID | Type | Specialty | State | Due date |
|---|---|---|---|---|
| I20031230000277 | I | Family Practice | CA | TBD |
What to do next
- No action required while the due date shows TBD.
- Check the CMS Revalidation Lookup Tool periodically — CMS updates the list about every 60 days.
- Do not submit a revalidation application in PECOS until CMS publishes a concrete due date.
Prepare CMS-855 application → · Look up this NPI in PECOS → · Verify on CMS PECOS
Medicare Utilization (FFS)
Source: CMS public data · Not endorsed by CMS · Beneficiary counts under 11 are suppressed in source data ·
Educational use only—not medical, billing, or legal advice.
Top Medicare procedures (2023) · refreshed 2026-05-27
| HCPCS | Description | Services | Beneficiaries | Medicare allowed |
|---|---|---|---|---|
| 99497 | Advance care planning, first 30 minutes | 223 | 24 | $0 |
| 99213 | Established patient office or other outpatient visit, 20-29 minutes | 171 | 71 | $0 |
| 99308 | Subsequent nursing facility care with straightforward level of medical decision making, per day, if using time, at least 15 minutes | 165 | 22 | $0 |
| 99348 | Residence visit for established patient with low level of medical decision making, per day, if using time, at least 30 minutes | 129 | 13 | $0 |
| 99442 | Telephone medical discussion with physician, 11-20 minutes | 52 | 25 | $0 |
Insurance plans in this area (ZIP 91763)
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Group practice members
| Name | Specialty | State |
|---|---|---|
| Nurse Practitioner | CA |
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