Walter S. Tjoa, MD
Dermatology Physician · Fontana, CA
Walter S. Tjoa, MD is a dermatology physician with a practice address in Fontana, California, and NPI 1801955463, issued on Dec 8, 2006. Check the license (California C42142, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Walter S. Tjoa
- Credential
- MD
- Primary taxonomy
- Dermatology Physician 207N00000X
- License number
- C42142 CA
Self-reported in NPPES; status is on the state search - Practice location
- 9961 Sierra Ave, Fontana, CA 92335
- Phone
- (909) 427-3910
- Enumerated
- Dec 8, 2006
- Record last updated
- Nov 18, 2021 (not updated in 5 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest dermatology physician records → All 2,083 in California → Look up another NPI →
Also registered at 9961 Sierra Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Walter S. Tjoa in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license C42142Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Industry payments in 2024: $16.00
1 payment: food and beverage; the largest payer was Leo Pharma Inc. The 10,250 providers of this specialty with any payment received $8,544.61 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Walter S. Tjoa among 2,083 dermatology physician records in California
Walter S. Tjoa, MD is one of 2,083 dermatology physician records with a practice address in California. 83% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 6% of them.
- NPI issued2006 · 6% of these records are older, 56% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileNo · 70% of these records are
- Record last updated2021 · 58% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207N00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Dermatology Physician providers in California
There are 2,083 dermatology physician records in California.
All 2,083 in California → Every provider in Fontana → Dermatology Physician nationwide →
The 8 dermatology physician records with the nearest ZIP codes
- Monika Curlin, MDFontana, CA 923351023189081
- Phillip Hsu, M.D.Fontana, CA 923351366400574
- Lewis Kramer, MDFontana, CA 923351255408266
- Linh Lu, MDFontana, CA 923351548316144
- William Sharra III, MDFontana, CA 923351376610246
- Emily Tang, MDFontana, CA 923351598824153
- Yun TongFontana, CA 923351700220902
- Zhi-Gang Wei, MDFontana, CA 923351831258417
Common questions
What is Walter S. Tjoa, MD's NPI number?
Walter S. Tjoa, MD's National Provider Identifier (NPI) is 1801955463, issued on Dec 8, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Walter S. Tjoa, MD located?
The NPPES record lists a practice address at 9961 Sierra Ave, Fontana, CA, 92335. Phone: (909) 427-3910. Providers update this record themselves, so call before visiting.
How can I verify Walter S. Tjoa, MD's license?
NPPES lists California license number C42142, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.