Mark Zaslav, PH.D.
Mark Zaslav, PH.D. is an Addiction (Substance Use Disorder) Psychologist in Corte Madera, CA, registered under NPI 1255486270. This provider registers 3 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 21 TAMAL VISTA BLVD STE 120, Corte Madera, CA 94925. 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 |
|---|---|---|
| PSY 9205 | CA | Addiction (Substance Use Disorder)… primary |
| PSY 9205 | CA | Clinical Psychologist |
| PSY 9205 | CA | Forensic Psychologist |
This provider holds licence PSY 9205 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 Addiction (Substance Use Disorder) covers
A psychologist with a proficiency that involves the application of psychological treatment of addiction stemming from the use of alcohol and other psychoactive substances (e.g., nicotine, marijuana, cocaine, heroin) or behavioral addictions (e.g., gambling) with the aim of cessation or reduction of use and/or the amelioration of emotional, behavioral, interpersonal and other problems arising from the addictive behavior. NUCC Health Care Provider Taxonomy, code 103TA0400X
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 | |
|---|---|---|---|---|
| 103TA0400X | Addiction (Substance Use Disorder) Psychologist Addiction (Substance Use Disorder) | PSY 9205 | CA | primary |
| 103TC0700X | Clinical Psychologist Clinical | PSY 9205 | CA | |
| 103TF0200X | Forensic Psychologist Forensic | PSY 9205 | 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 | 1255486270 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jan 23, 2007 |
| Last updated | Sep 11, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | PH.D. |
| Practice address |
21 TAMAL VISTA BLVD STE 120 Corte Madera, CA 94925 (415) 927-1560 |
| Mailing address |
2 GLEN WAY Larkspur, CA 94939 |
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 | 2 | 5 | 5 | 4 | 8 | 6 | 2 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 2 | 1 | 5 | 8 | 8 | 3 | 2 | 5 |
Sum = 60 · next multiple of 10 = 60 · 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.