William J. Tsai, M.D.
Internal Medicine Physician · Irvine, CA
William J. Tsai, M.D. is an internal medicine physician with a practice address in Irvine, California, and NPI 1952356560, issued on May 23, 2006. Check the license (California A71679, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- William J. Tsai
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A71679 CA
Self-reported in NPPES; status is on the state search - Practice location
- 19742 Macarthur Blvd, Irvine, CA 92612
- Phone
- (949) 955-0202
- Enumerated
- May 23, 2006
- Record last updated
- Jul 16, 2010 (not updated in 16 years: call before relying on the address or phone)
- Fax
- (949) 955-0203
- Medicaid ID
- 00A716790 CA
- Medicare enrollment
- Enrolled (PECOS I20031126000678); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 19742 Macarthur Blvd
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Patricia Kovars, M.F.T.Marriage & Family Therapist1922150747
- Gracie Lu, LCSWClinical Social Worker1225381668
Verify William J. Tsai in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A71679Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.7 times the Medicare Part D claims of the average internal medicine physician in 2024
8,525 Medicare Part D claims for 703 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 10% of claims. 116 claims were for opioids.
Most prescribed
- Atorvastatin Calcium731 claims
- Levothyroxine Sodium380 claims
- Amlodipine Besylate376 claims
- Zolpidem Tartrate288 claims
- Losartan Potassium283 claims
- Rosuvastatin Calcium276 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 16.1 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $182.31
4 payments; by number, the most common kind was food and beverage; the largest payer was Amgen Inc. The 50,334 providers of this specialty with any payment received $1,303.06 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.
William J. Tsai among 17,696 internal medicine physician records in California
William J. Tsai, M.D. is one of 17,696 internal medicine physician records with a practice address in California. 79% 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 5% of them.
- NPI issued2006 · 5% of these records are older, 56% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1997 · median 2004 among the 11,065 with a school on file
- Record last updated2010 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
155 internal medicine physician records list a practice address in Irvine
They are 155 of the 7,778 NPPES records with a practice address in Irvine, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Irvine → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Susan Davoodifar, M.D.Irvine, CA 926121013287119
- Pamela Lawrence, M.D.Irvine, CA 926121336299734
- Marta Long, MDIrvine, CA 926121205860509
- Juliana Mathewson, M.D.Irvine, CA 926121275709594
- Grace Chang, M.D.Irvine, CA 926141992877625
- Denny Lee, MDIrvine, CA 926141740571835
- Maulik Majmudar, M.D.Irvine, CA 926141346395100
- Firas Naji, D.O.Irvine, CA 926141578883997
Common questions
What is William J. Tsai, M.D.'s NPI number?
William J. Tsai, M.D.'s National Provider Identifier (NPI) is 1952356560, issued on May 23, 2006. An NPI identifies a provider in billing; it is not a license.
Where is William J. Tsai, M.D. located?
The NPPES record lists a practice address at 19742 Macarthur Blvd, Irvine, CA, 92612. Phone: (949) 955-0202. Providers update this record themselves, so call before visiting.
How can I verify William J. Tsai, M.D.'s license?
NPPES lists California license number A71679, 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.
How much does William J. Tsai, M.D. prescribe under Medicare Part D?
In 2024, William J. Tsai, M.D. had 8,525 Medicare Part D claims for 703 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
What is William J. Tsai, M.D.'s MIPS final score?
The 2023 MIPS final score is 16.1 of 100. The average among 454,083 clinicians with a measured score was 83.5.
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.