Jason Joseph Gajarsa, M.D.
Internal Medicine Physician · Fountain Valley, CA
Jason Joseph Gajarsa, M.D. is an internal medicine physician with a practice address in Fountain Valley, California, and NPI 1427256577, issued on Jul 10, 2007. Check the license (California A99066, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Jason Joseph Gajarsa
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A99066 CA
Self-reported in NPPES; status is on the state search - Practice location
- 11180 Warner Ave, Fountain Valley, CA 92708
- Phone
- (714) 751-3540
- Enumerated
- Jul 10, 2007
- Record last updated
- Nov 3, 2021 (not updated in 5 years: call before relying on the address or phone)
- Medicare enrollment
- Enrolled (PECOS I20091012000265); accepts Medicare assignment
- Medical or professional school
- Georgetown University School Of Medicine, 2004
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 11180 Warner Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Jason Joseph Gajarsa in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A99066Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
3% more Medicare Part D claims than the average internal medicine physician in 2024
3,267 Medicare Part D claims for 591 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
Most prescribed
- Metoprolol Tartrate264 claims
- Pradaxa245 claims
- Losartan Potassium229 claims
- Atorvastatin Calcium205 claims
- Carvedilol184 claims
- Bisoprolol Fumarate169 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.
Bills Medicare through one group practice
- Southern California Permanente Medical GroupHarbor City, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Jason Joseph Gajarsa among 17,696 internal medicine physician records in California
Jason Joseph Gajarsa, 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 2007, is newer than 44% of them.
- NPI issued2007 · 44% of these records are older, 44% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2004 · median 2004 among the 11,065 with a school on file
- Record last updated2021 · 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).
83 internal medicine physician records list a practice address in Fountain Valley
They are 83 of the 2,190 NPPES records with a practice address in Fountain Valley, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Fountain Valley → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Joel Bartlett, MDFountain Valley, CA 927081073518791
- Ihong Chen, MDFountain Valley, CA 927081104822535
- Naomi Cheung, MDFountain Valley, CA 927081073503314
- Alan Dang, M.D.Fountain Valley, CA 927081043217359
- Alton ForanFountain Valley, CA 927081619968799
- George Hong, MDFountain Valley, CA 927081154328532
- Brandon Khaw, MDFountain Valley, CA 927081568453637
- Lalita Komanapalli, MDFountain Valley, CA 927081578560884
Common questions
What is Jason Joseph Gajarsa, M.D.'s NPI number?
Jason Joseph Gajarsa, M.D.'s National Provider Identifier (NPI) is 1427256577, issued on Jul 10, 2007. An NPI identifies a provider in billing; it is not a license.
Where is Jason Joseph Gajarsa, M.D. located?
The NPPES record lists a practice address at 11180 Warner Ave, Fountain Valley, CA, 92708. Phone: (714) 751-3540. Providers update this record themselves, so call before visiting.
How can I verify Jason Joseph Gajarsa, M.D.'s license?
NPPES lists California license number A99066, 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 Jason Joseph Gajarsa, M.D. prescribe under Medicare Part D?
In 2024, Jason Joseph Gajarsa, M.D. had 3,267 Medicare Part D claims for 591 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
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.