Gerald Tarder, M.D.
Gerald Tarder, M.D. is a Gastroenterology Physician in Walnut Creek, CA, registered under NPI 1396833984. 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 130 LA CASA VIA STE 107, Walnut Creek, CA 94598. 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 |
|---|---|---|
| G26001 | CA | Gastroenterology Physician primary |
This provider holds licence G26001 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 - Gastroenterology
- PAC ID
- 8729070800
- Enrollment ID
- I20040330001806
Medicare enrolment is recorded as approved under the provider type Practitioner - Gastroenterology. 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 Gastroenterology covers
An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This specialist treats conditions such as abdominal pain, ulcers, diarrhea, cancer and jaundice and performs complex diagnostic and therapeutic procedures using endoscopes to visualize internal organs. NUCC Health Care Provider Taxonomy, code 207RG0100X
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 | 1396833984 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Oct 10, 2006 |
| Last updated | Jul 8, 2007 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D. |
| Practice address |
130 LA CASA VIA STE 107 Walnut Creek, CA 94598 (925) 938-6060 Fax (925) 938-0119 |
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 | 3 | 9 | 6 | 8 | 3 | 3 | 9 | 8 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 3 | 9 | 6 | 7 | 3 | 6 | 9 | 7 |
Sum = 76 · next multiple of 10 = 80 · check digit = 4 · actual last digit = 4
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.