William Diehl, M.D.
William Diehl, M.D. is a Surgical Oncology Physician in Livingston, NJ, registered under NPI 1629068457. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty.
Getting there
The practice address on file is 75 E NORTHFIELD RD, Livingston, NJ 07039. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 25MA04355800 | NJ | Surgical Oncology Physician primary |
| 25MA04355800 | NJ | Surgery Physician |
This provider holds licence 25MA04355800 issued in NJ. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - General Surgery
- PAC ID
- 7113962267
Medicare enrolment is recorded as approved under the provider type Practitioner - General Surgery. This means the provider is enrolled to bill Medicare, though it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Surgical Oncology covers
A surgical oncologist is a well-qualified surgeon who has obtained additional training and experience in the multidisciplinary approach to the prevention, diagnosis, treatment, and rehabilitation of cancer patients, and devotes a major portion of his or her professional practice to these activities and cancer research. NUCC Health Care Provider Taxonomy, code 2086X0206X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2086X0206X | Surgical Oncology Physician Surgical Oncology | 25MA04355800 | NJ | primary |
| 208600000X | Surgery Physician | 25MA04355800 | NJ |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1629068457 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Oct 24, 2005 |
| Last updated | Feb 16, 2026 |
| Status | Active |
| Sole proprietor | No |
| Credential | M.D. |
| Practice address |
75 E NORTHFIELD RD Livingston, NJ 07039 (973) 436-1530 Fax (973) 422-0414 |
| Mailing address |
261 JAMES ST SUITE 2G Morristown, NJ 07960 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 6 | 2 | 9 | 0 | 6 | 8 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 6 | 4 | 9 | 0 | 6 | 7 | 4 | 1 |
Sum = 63 · next multiple of 10 = 70 · check digit = 7 · actual last digit = 7
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.