Quick answers
- Does Jeffrey M. Niizawa accept Medicare assignment?
- Yes. Medicare's clinician data says Jeffrey M. Niizawa accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- What is Jeffrey M. Niizawa's NPI number?
- 1922015445. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Jeffrey M. Niizawa works
Medicare's Facility Affiliation Data lists Jeffrey M. Niizawa at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Kaiser Foundation Hospital - VacavilleVacaville, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050767
Practice locations
Addresses where Jeffrey M. Niizawa is enrolled with Medicare (CMS data updated October 2, 2026). The first 5 of 8; the Medicare profile lists all.
- 26421 Crown Valley Pkwy, Suite 140aMission Viejo, CA 92691 (949) 365‑8836
- 3430 E La Palma AveAnaheim, CA 92806 (888) 988‑2800
- 3460 E La Palma AveAnaheim, CA 92806 (714) 644‑2010
- 5475 E La Palma AveAnaheim, CA 92807 (714) 279‑6088
- 6640 Alton PkwyIrvine, CA 92618 (949) 932‑5000
Group practices
Medicare enrollment lists Jeffrey M. Niizawa as a member of these groups (CMS data updated October 2, 2026).
- Southern California Permanente Medical Group11,293 clinicians in the group
- Permanente Medical Group Inc10,996 clinicians in the group
- Om P. Chaurasia, MD, Inc.7 clinicians in the group
Specialties
- Internal Medicineprimary
- Gastroenterologyalso
Other internal medicine doctors in Mission Viejo
Clinicians with the same Medicare primary specialty in Mission Viejo, CA — not a recommendation.
Other clinicians in Southern California Permanente Medical Group
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Northwestern University Feinberg Medical School |
| Graduation year | 1988 (38 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1922015445 |
| 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
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- 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