Quick answers
- Where does William K. Marek see patients?
- Medicare's clinician data lists 3 practice locations, including Mill Valley, CA and Santa Clara, CA. Call before your visit to confirm the address.
- What is William K. Marek's specialty?
- Medicare lists Clinical Psychologist as the primary specialty.
- Does William K. Marek accept Medicare assignment?
- Yes. Medicare's clinician data says William K. Marek accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- Does William K. Marek offer telehealth?
- Medicare's clinician data says William K. Marek offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for William K. Marek?
- (925) 275-0290, as listed in official Medicare / NPI Registry data.
- What is William K. Marek's NPI number?
- 1851560544. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where William K. Marek is enrolled with Medicare (CMS data updated 2026-10-02).
- 214 Laverne AveMill Valley, CA 94941 (925) 275‑0290
- 4633 Old Ironsides Dr, Suite 304Santa Clara, CA 95054 (866) 280‑0260
- 5201 Great America Pkwy, Suite 320Santa Clara, CA 95054 (323) 968‑6182
Group practices
Medicare enrollment lists William K. Marek as a member of this group (CMS data updated 2026-10-02).
- Sud Specialty Group - Ca568 clinicians in the group
Specialties
- Clinical Psychologistprimary
Other clinical psychologists in Mill Valley
Clinicians with the same Medicare primary specialty in Mill Valley, CA — not a recommendation.
Clinician information
| Graduation year | 1989 |
|---|---|
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1851560544 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians