Ji Won Ahn, MD
Ji Won Ahn, MD is a MOHS-Micrographic Surgery Physician in Walnut Creek, CA, registered under NPI 1023460243.
Getting there
The practice address on file is 320 LENNON LN DEPT OF, 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 |
|---|---|---|
| 66941 | MN | MOHS-Micrographic Surgery Physician primary |
This provider holds licence 66941 issued in MN. 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 - Dermatology
- PAC ID
- 2466748579
Medicare enrolment is recorded as approved under the provider type Practitioner - Dermatology. 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 MOHS-Micrographic Surgery covers
The highly-trained surgeons that perform Mohs Micrographic Surgery are specialists both in dermatology and pathology. With their extensive knowledge of the skin and unique pathological skills, they are able to remove only diseased tissue, preserving healthy tissue and minimizing the cosmetic impact of the surgery. Mohs surgeons who belong to the American College of Mohs Surgery (ACMS) have completed a minimum of one year of fellowship training at one of the ACMS-approved training centers in the U.S. NUCC Health Care Provider Taxonomy, code 207ND0101X
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 | 1023460243 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 12, 2016 |
| Last updated | Oct 30, 2024 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
320 LENNON LN DEPT OF Walnut Creek, CA 94598 (925) 817-5678 |
| Mailing address |
200 1ST ST SW Rochester, MN 55905 |
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 | 0 | 2 | 3 | 4 | 6 | 0 | 2 | 4 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 4 | 3 | 8 | 6 | 0 | 2 | 8 |
Sum = 57 · next multiple of 10 = 60 · check digit = 3 · actual last digit = 3
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.