William Charles O'Callahan Jr., MD
NPI 1114964186ActiveIndividual· Emergency Medicine· Holden, MA
Emergency Medicine (MD) in Holden, Massachusetts, trained at University of Massachusetts Medical School (class of 1990). 511 Medicare patients in 2024, $73,490 paid; nearly all of their 849 Part D prescriptions were generic (94%).
Overview
| NPI | 1114964186 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | May 31, 2006 |
| Last updated in NPPES | Oct 4, 2026 |
| Certified by provider | Oct 4, 2026 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Emergency Medicine Primary | 207P00000X | 79001 | MA |
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 - Emergency Medicine (MA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 511 |
|---|---|
| Services billed | 1,147 across 55 procedure codes |
| Paid by Medicare | $73,490 |
Part D prescriptions in 2024
| Prescriptions (claims) | 849 · 864 30-day fills |
|---|---|
| Patients | 594 |
| Total drug cost | $8,787 |
| Generic share | 94% of claims |
Education and affiliations
| Medical school | University of Massachusetts Medical School |
|---|---|
| Graduation year | 1990 |
| Medicare specialty | Emergency Medicine |
Medical group
- Urgent Care Specialists PCWilbraham, MA · 10 clinicians
Hospital affiliation
- Umass Memorial Medical Center/University CampusWorcester, MA
Industry payments (Open Payments)
None reported for 2025 or 2024.
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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