William Tan Nguyen, M.D.
NPI 1043424575ActiveIndividual· Internal Medicine· Orange, CA
Internal Medicine (M.D.) with Southern California Permanente Medical Group, practicing in Orange, California. Their prescriptions cost Medicare Part D more than their services did: $258,361 for 935 claims, against $3,405 paid for services in 2024. Regeneron Healthcare Solutions, Inc. was the largest of 2 companies reporting payments in 2025, $56.89 in all, mostly food and beverage.
Overview
| NPI | 1043424575 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | Yes |
| NPI issued | May 10, 2007 |
| Last updated in NPPES | Nov 4, 2021 |
| Certified by provider | Nov 4, 2021 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | A98370 | 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 - Gastroenterology (CA); Practitioner - Internal Medicine (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 14 |
|---|---|
| Services billed | 27 across 13 procedure codes |
| Paid by Medicare | $3,405 |
Part D prescriptions in 2024
| Prescriptions (claims) | 935 · 1,802 30-day fills |
|---|---|
| Patients | 425 |
| Total drug cost | $258,361 |
| Generic share | 87% of claims |
Education and affiliations
| Graduation year | 2005 |
|---|---|
| Medicare specialty | Internal Medicine |
| Secondary specialties | Gastroenterology |
Medical group
- Southern California Permanente Medical GroupRedlands, CA · 11,293 clinicians
Industry payments (Open Payments)
- 2025$56.89 · 2 payments from 2 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Regeneron Healthcare Solutions, Inc. | $31.10 | 1 |
| Phathom Pharmaceuticals, Inc. | $25.79 | 1 |
What the 2025 payments were for
- Food and Beverage$56.89 · 2 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All 224 internal medicine physicians in Orange · All internal medicine physicians in California