DR. GEMMA GUILLERMO M.D.
NPI 1831154418
Psychiatry & Neurology - Psychiatry in Redwood City, CA
About Dr. Gemma Guillermo M.d. NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
DR. GEMMA GUILLERMO M.D. (NPI 1831154418) is an individual psychiatry provider in Redwood City, California, licensed in California (61066) and active in the NPI registry since April 2006. She is enrolled in Medicare PECOS and is a graduate of Js Weill Medical College, Cornell University (1995).
NPPES Registry Identity
Specialties & Licenses
Other Identifiers 1
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Dr. Gemma Guillermo M.d. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
2Medicare enrollment records show Gemma Guillermo reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Redwood City, CA 94063
- Reassigned Medicare billing, California enrollment
- Medicare enrollment name: County Of San Mateo
- 597 clinicians in this Medicare group
Palo Alto, CA 94306
- Reassigned Medicare billing, California enrollment
- 2,460 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims 5
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Physician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 94062 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Medicare Quality Performance CMS QPP · MIPS
Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
REDWOOD CITY, CA 94062
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Gemma Guillermo's NPI number?
The NPI number for Gemma Guillermo is 1831154418. It was assigned to this individual provider in the NPPES registry on April 18, 2006.
Where is Gemma Guillermo located?
Gemma Guillermo practices at 170 Alameda De Las Pulgas 1east, Sequoia Hospital, Redwood City, CA 94062. The listed phone number is (650) 367-5559.
What is Gemma Guillermo's specialty?
The primary specialty registered for this NPI is Psychiatry & Neurology, specializing in Psychiatry, with taxonomy code 2084P0800X.
Is Gemma Guillermo enrolled in Medicare?
Yes. Gemma Guillermo is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Gemma Guillermo's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Gemma Guillermo reassigns Medicare benefits to 2 organizations: San Mateo County (Redwood City, CA) and County Of Santa Clara (Palo Alto, CA). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Gemma Guillermo's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
When was this NPI record last updated?
The NPPES record for Gemma Guillermo was last updated on February 13, 2019. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 7 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Dr. Gemma Guillermo, M.D. · NPI 1831154418
Psychiatry physician in Redwood City, California. Individual provider, active in the CMS NPPES registry since April 18, 2006.
## Identity
- **NPI:** 1831154418 (Entity type: Individual)
- **Enumerated:** April 18, 2006
- **Primary specialty:** Psychiatry & Neurology - Psychiatry · taxonomy 2084P0800X
- **State license:** 61066 (California)
- **Sole proprietor:** Yes
## Practice location
- **Address:** 170 ALAMEDA DE LAS PULGAS, 1EAST, SEQUOIA HOSPITAL, Redwood City, CA 94062-2799
- **Phone:** (650) 367-5559 · **Fax:** (650) 368-3754
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 2 organizations under Medicare reassignment (form CMS-855R): San Mateo County (NPI 1912926692, Redwood City, CA); County Of Santa Clara (NPI 1144330614, Palo Alto, CA) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Js Weill Medical College, Cornell University, class of 1995
## Record status
- **NPPES last updated:** February 13, 2019
- **Other identifiers:** Medicaid 3967836 (CA)
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Source: [NPI Profile](https://npiprofile.com/npi/1831154418) · Data from the CMS NPPES public registry.