William Mares
William Mares is a provider specialising in Clinical Social Worker in Fremont, CA, registered under NPI 1376914960. 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 39199 LIBERTY ST, Fremont, CA 94538. 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 |
|---|---|---|
| 84439 | CA | Clinical Social Worker primary |
| 66815 | CA | Social Worker |
| 84439 | CA | Social Worker |
This provider holds licence 84439 issued in CA. 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 Clinical covers
A social worker who holds a master's or doctoral degree in social work from an accredited school of social work in addition to at least two years of post-master's supervised experience in a clinical setting. The social worker must be licensed, certified, or registered at the clinical level in the jurisdiction of practice. A clinical social worker provides direct services, including interventions focused on interpersonal interactions, intrapsychic dynamics, and life management issues. Clinical social work services are based on bio-psychosocial perspectives. Services consist of assessment, diagnosis, treatment (including psychotherapy and counseling), client-centered advocacy, consultation, evaluation, and prevention of mental illness, emotional, or behavioral disturbances. NUCC Health Care Provider Taxonomy, code 1041C0700X
All registered taxonomy codes
This provider registers 3 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 1041C0700X | Clinical Social Worker Clinical | 84439 | CA | primary |
| 104100000X | Social Worker | 66815 | CA | |
| 104100000X | Social Worker | 84439 | 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 | 1376914960 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Oct 8, 2015 |
| Last updated | May 19, 2022 |
| Status | Active |
| Sole proprietor | Yes |
| Practice address |
39199 LIBERTY ST Fremont, CA 94538 (209) 303-7341 |
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 | 7 | 6 | 9 | 1 | 4 | 9 | 6 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 3 | 5 | 6 | 9 | 1 | 8 | 9 | 3 |
Sum = 70 · next multiple of 10 = 70 · check digit = 0 · actual last digit = 0
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.