WILLIAM TSAI D O INC
NPI 1598876856
Family Medicine in Upland, CA

Q: What is William Tsai D O Inc's NPI number?

The NPI number for William Tsai D O Inc is 1598876856. It was assigned to this organization in the NPPES registry on August 31, 2006.

Q: What is William Tsai D O Inc's specialty?

The primary specialty registered for this NPI is Family Medicine with taxonomy code 207Q00000X.

Active since August 31, 2006

510 N 13TH AVE STE 101, UPLAND, CA 91786(909) 985-8838 Get Directions Write a Review

NPPES record last updated: April 24, 2024. Verified against the NPPES registry weekly; last sync: November 01, 2026.

Record update history: Apr 24, 2024, Aug 22, 2020 (2 updates tracked since 2020).

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About William Tsai D O Inc NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

WILLIAM TSAI D O INC (NPI 1598876856) is a healthcare organization registered as a family medicine in Upland, California and active in the NPI registry since August 2006. The organization lists William Tsai, Physician Owner, as its authorized official.

NPPES Registry Identity

NPI1598876856

Entity TypeOrganization

Primary Taxonomy207Q00000X

Legal Business NameWILLIAM TSAI D O INC

Location Address510 N 13TH AVE STE 101Upland, CA 91786-4973

Mailing Address510 N 13th Ave Ste 101Upland, CA 91786-4973 · (909) 985-8838

Phone(909) 985-8838

Organization SubpartNo

Authorized OfficialWilliam TsaiPhysician Owner · (909) 985-8838

Enumeration DateAugust 31, 2006

Last NPPES UpdateApril 24, 20242 updates tracked since enumeration

NPPES CertifiedApril 24, 2024

✔ NPI 1598876856 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyFamily MedicineAllopathic & Osteopathic Physicians

Taxonomy Code207Q00000X

License✔ Licensed in CA · 20A7115

Definition

Family Medicine is the medical specialty which is concerned with the total health care of the individual and the family. It is the specialty in breadth which integrates the biological, clinical, and behavioral sciences. The scope of family medicine is not limited by age, sex, organ system, or disease entity.

510 N 13TH AVE STE 101, Upland, CA 91786

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Other Identifiers 1

Medicaid00AX71150CA

Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

William Tsai D O Inc is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Clinicians Billing Medicare Through This Organization

Medicare enrollment records show 4 clinicians reassign Medicare billing to William Tsai D O Inc, which bills Medicare for the services they deliver. Of these, 3 practice at this address. They are listed nearest first.

Clinicians, nearest first (4)

William Tsai, D.O.

Family Practice

NPI 1285620443

510 N 13TH AVE STE 101
Upland, CA 91786

(909) 985-8838

✔ PECOS✔ Accepts MedicareSame address

Lisa Chi

Nurse Practitioner

NPI 1275483091

510 N 13TH AVE STE 101
Upland, CA 91786

(909) 985-8838

✔ PECOS✔ Accepts MedicareSame address

Jie Lin

Nurse Practitioner

NPI 1396607727

510 N 13TH AVE STE 101
Upland, CA 91786

(909) 985-8838

✔ PECOSSame address

Dinh Lai

Nurse Practitioner

NPI 1093123176

1749 N GARVEY AVE
Pomona, CA 91767

(909) 729-5079

✔ PECOS✔ Accepts Medicare16 mi

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

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 William Tsai D O Inc's NPI number?

The NPI number for William Tsai D O Inc is 1598876856. It was assigned to this organization in the NPPES registry on August 31, 2006.

Where is William Tsai D O Inc located?

William Tsai D O Inc is located at 510 N 13th Ave Ste 101, Upland, CA 91786. The listed phone number is (909) 985-8838.

What is William Tsai D O Inc's specialty?

The primary specialty registered for this NPI is Family Medicine with taxonomy code 207Q00000X.

Is William Tsai D O Inc enrolled in Medicare?

Yes. William Tsai D O Inc is registered in the Medicare PECOS enrollment system.

How many clinicians bill Medicare through William Tsai D O Inc?

According to the CMS Revalidation Reassignment List (October 2026 release), 4 clinicians in 2 Medicare specialties reassign their Medicare billing to William Tsai D O Inc. A 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 the clinician's services. The largest specialties are Nurse Practitioner (3) and Family Practice (1). Of these, 3 practice at this address. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

When was this NPI record last updated?

The NPPES record for William Tsai D O Inc was last updated on April 24, 2024. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 2 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.