William Hahn, M.D.
William Hahn, M.D. is an Infectious Disease Physician in Santa Barbara, CA, registered under NPI 1386215655.
Getting there
The practice address on file is SANTA BARBARA COTTAGE HOSPITAL 400 W. PUEBLO STREET, Santa Barbara, CA 93105. 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 |
|---|---|---|
| 353196 | LA | Infectious Disease Physician primary |
This provider holds licence 353196 issued in LA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What Infectious Disease covers
An internist who deals with infectious diseases of all types and in all organ systems. Conditions requiring selective use of antibiotics call for this special skill. This physician often diagnoses and treats AIDS patients and patients with fevers which have not been explained. Infectious disease specialists may also have expertise in preventive medicine and travel medicine. NUCC Health Care Provider Taxonomy, code 207RI0200X
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 | 1386215655 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 7, 2021 |
| Last updated | Aug 19, 2026 |
| Status | Active |
| Sole proprietor | No |
| Gender | Male |
| Credential | M.D. |
| Practice address |
SANTA BARBARA COTTAGE HOSPITAL 400 W. PUEBLO STREET Santa Barbara, CA 93105 (805) 569-7315 Fax (805) 569-8358 |
| Mailing address |
400 W PUEBLO ST Santa Barbara, CA 93105 |
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 | 8 | 6 | 2 | 1 | 5 | 6 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 3 | 7 | 6 | 4 | 1 | 1 | 6 | 1 |
Sum = 55 · next multiple of 10 = 60 · check digit = 5 · actual last digit = 5
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.