William Chen, M.D.
NPI 1881659142ActiveIndividual· Internal Medicine· Irvine, CA
Internal Medicine (M.D.) in Irvine, California, trained at University of Southern California Keck School of Medicine (class of 2000). Their prescriptions cost Medicare Part D more than their services did: $128,048 for 2,043 claims, against $3,763 paid for services in 2024. Baxter Healthcare was the largest of 2 companies reporting payments in 2025, $79.25 in all, mostly food and beverage.
Overview
| NPI | 1881659142 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | No |
| NPI issued | Apr 19, 2006 |
| Last updated in NPPES | Dec 1, 2021 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | A93575 | CA |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Nov 10, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 11, 2026 | No match | — |
| New York OMIG · Nov 11, 2026 | No match | — |
| Ohio Medicaid · Nov 11, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 11, 2026 | No match | — |
| Washington HCA · Nov 11, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Internal Medicine (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 13 |
|---|---|
| Services billed | 29 across 7 procedure codes |
| Paid by Medicare | $3,763 |
Part D prescriptions in 2024
| Prescriptions (claims) | 2,043 · 5,954 30-day fills |
|---|---|
| Patients | 358 |
| Total drug cost | $128,048 |
| Generic share | 95% of claims |
Education and affiliations
| Medical school | University of Southern California Keck School of Medicine |
|---|---|
| Graduation year | 2000 |
| Medicare specialty | Internal Medicine |
Medical group
- Southern California Permanente Medical GroupRedlands, CA · 11,293 clinicians
Hospital affiliation
Industry payments (Open Payments)
- 2025$79.25 · 2 payments from 2 companies
- 2024$102.26 · 1 payment from 1 company
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Baxter Healthcare | $58.91 | 1 |
| Salix Pharmaceuticals, A Division of Bausch Health US, LLC | $20.34 | 1 |
What the 2025 payments were for
- Food and Beverage$79.25 · 2 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All 207 internal medicine physicians in Irvine · All internal medicine physicians in California