DR. GERALDINE GAN TAN MD
NPI 1699744086
Hospitalist in Walnut Creek, CA
About Dr. Geraldine Gan Tan Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
DR. GERALDINE GAN TAN MD (NPI 1699744086) is an individual hospitalist provider in Walnut Creek, California, licensed in California (A81859) and active in the NPI registry since March 2006. She is enrolled in Medicare PECOS.
NPPES Registry Identity
Specialties & Licenses 2
Other Identifiers 6
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare (PECOS)
Dr. Geraldine Gan Tan Md is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Medicare Billing Reassignments
3Medicare enrollment records show Geraldine Tan reassigns Medicare billing to 3 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Walnut Creek, CA 94598
- Reassigned Medicare billing, California enrollment
- 810 clinicians in this Medicare group
Walnut Creek, CA 94597
- Reassigned Medicare billing, California enrollment
- 650 clinicians in this Medicare group
Berkely, CA 94710
- Reassigned Medicare billing, California enrollment
- 4 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.
Physician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 94595 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
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.
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 Geraldine Tan's NPI number?
The NPI number for Geraldine Tan is 1699744086. It was assigned to this individual provider in the NPPES registry on March 16, 2006.
Where is Geraldine Tan located?
Geraldine Tan practices at 1220 Rossmoor Pkwy, Walnut Creek, CA 94595. The listed phone number is (925) 947-3393.
What is Geraldine Tan's specialty?
The primary specialty registered for this NPI is Hospitalist with taxonomy code 208M00000X.
Is Geraldine Tan enrolled in Medicare?
Yes. Geraldine Tan is registered in the Medicare PECOS enrollment system.
Which organizations bill Medicare for Geraldine Tan's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Geraldine Tan reassigns Medicare benefits to 3 organizations: John Muir Trauma Physicians Billing Service (Walnut Creek, CA), John Muir Physician Network (Walnut Creek, CA) and Inpatient Consultants Of California, Inc. (Berkely, 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 Geraldine Tan'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 Geraldine Tan was last updated on September 29, 2015. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 11 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. Geraldine Gan Tan, MD · NPI 1699744086
Hospitalist physician in Walnut Creek, California. Individual provider, active in the CMS NPPES registry since March 16, 2006.
## Identity
- **NPI:** 1699744086 (Entity type: Individual)
- **Enumerated:** March 16, 2006
- **Primary specialty:** Hospitalist · taxonomy 208M00000X
- **State license:** A81859 (California)
- **Sole proprietor:** No
## Practice location
- **Address:** 1220 ROSSMOOR PKWY, Walnut Creek, CA 94595-2501
- **Phone:** (925) 947-3393 · **Fax:** (925) 947-3396
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 3 organizations under Medicare reassignment (form CMS-855R): John Muir Trauma Physicians Billing Service (NPI 1093864837, Walnut Creek, CA); John Muir Physician Network (NPI 1841407665, Walnut Creek, CA); Inpatient Consultants Of California, Inc. (NPI 1831134253, Berkely, CA) · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** September 29, 2015
- **Other identifiers:** Medicare PIN 00A818590 (CA); Medicare PIN CA147127 (CA); Other P01495634 (CA); and 3 more
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Source: [NPI Profile](https://npiprofile.com/npi/1699744086) · Data from the CMS NPPES public registry.