Timothy Chang, MD
Timothy Chang, MD is an Urology Physician in Stanford, CA, registered under NPI 1437594496. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 300 PASTEUR DR, Stanford, CA 94305. 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 |
|---|---|---|
| A131727 | CA | Urology Physician primary |
| A131727 | CA | Surgery Physician |
This provider holds licence A131727 issued in CA. 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 - Urology
- PAC ID
- 4880923010
- Enrollment ID
- I20190912001728
Medicare enrolment is recorded as approved under the provider type Practitioner - Urology. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Urology covers
A urologist manages benign and malignant medical and surgical disorders of the genitourinary system and the adrenal gland. This specialist has comprehensive knowledge of and skills in endoscopic, percutaneous and open surgery of congenital and acquired conditions of the urinary and reproductive systems and their contiguous structures. NUCC Health Care Provider Taxonomy, code 208800000X
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 | |
|---|---|---|---|---|
| 208800000X | Urology Physician | A131727 | CA | primary |
| 208600000X | Surgery Physician | A131727 | CA |
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 | 1437594496 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 5, 2013 |
| Last updated | Mar 13, 2024 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | MD |
| Practice address |
300 PASTEUR DR Stanford, CA 94305 (650) 725-5746 |
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 | 4 | 3 | 7 | 5 | 9 | 4 | 4 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 4 | 6 | 7 | 1 | 9 | 8 | 4 | 9 |
Sum = 74 · next multiple of 10 = 80 · check digit = 6 · actual last digit = 6
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.