James Michael Mason, MD
Radiation Oncology Physician · Wildomar, CA
James Michael Mason, MD is a radiation oncology physician with a practice address in Wildomar, California, and NPI 1902955818, issued on Jan 9, 2007. Check the license (California G85713, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- James Michael Mason
- Credential
- MD
- Primary taxonomy
- Radiation Oncology Physician 2085R0001X
- License number
- G85713 CA
Self-reported in NPPES; status is on the state search - Practice location
- 36450 Inland Valley Dr, Wildomar, CA 92595
- Phone
- (951) 696-0679
- Enumerated
- Jan 9, 2007
- Record last updated
- Nov 13, 2020 (not updated in 6 years: call before relying on the address or phone)
- Fax
- (951) 696-9748
- Medicaid ID
- 0961188 OH
- Medicare enrollment
- Enrolled (PECOS I20070810000801); accepts Medicare assignment
- Medical or professional school
- Wayne State University School Of Medicine, 1988
- Entity
- Type 1 · individual
8 nearest radiation oncology physician records → All 735 in California → Look up another NPI →
Also registered at 36450 Inland Valley Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Bassam Azzam, BS PHARMACYPharmacist1114466653
- Anh Brewer, D.O.Family Medicine Physician1487981569
- Blanca Casas, PAPhysician Assistant1649328568
- Kevin ChandrasenaInternal Medicine Physician1144614447
- David ChenPharmacist1912445818
- Sarah Devine-Cooter, FNPFamily Nurse Practitioner1023406675
Verify James Michael Mason in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G85713Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
74% fewer Medicare Part D claims than the average radiation oncology physician in 2024
35 Medicare Part D claims for 21 beneficiaries, against an average of 134 among the 4,851 providers of this specialty who prescribed in Part D.
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 practice group's MIPS final score for 2023 (Medicare payment program): 99.1 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. 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, group reporting; category weights for 2023 (qpp.cms.gov).
Bills Medicare through one group practice
- City OF Hope Medical FoundationWildomar, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
James Michael Mason among 735 radiation oncology physician records in California
James Michael Mason, MD is one of 735 radiation oncology 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 2007, is newer than 45% of them.
- NPI issued2007 · 45% of these records are older, 43% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileYes · 74% of these records are
- Graduated1988 · median 2005 among the 545 with a school on file
- Record last updated2020 · 55% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 2085R0001X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Radiation Oncology Physician providers in California
There are 735 radiation oncology physician records in California.
All 735 in California → Every provider in Wildomar → Radiation Oncology Physician nationwide →
The 8 radiation oncology physician records with the nearest ZIP codes
- Parima Daroui, M.D. PH.D.Wildomar, CA 925951629283841
- Jason Sun, M.D.Wildomar, CA 925951568691830
- Brian Ronson, MDTemecula, CA 925921750364493
- Tara Washington, MDTemecula, CA 925921780621276
- Colton Ladbury, MDIrvine, CA 926181891256756
- Percy Lee, M.D.Irvine, CA 926181447442504
- Harry Moyses, M.D.Irvine, CA 926181376522300
- Selamawit Negusse, MDIrvine, CA 926181316144041
Common questions
What is James Michael Mason, MD's NPI number?
James Michael Mason, MD's National Provider Identifier (NPI) is 1902955818, issued on Jan 9, 2007. An NPI identifies a provider in billing; it is not a license.
Where is James Michael Mason, MD located?
The NPPES record lists a practice address at 36450 Inland Valley Dr, Wildomar, CA, 92595. Phone: (951) 696-0679. Providers update this record themselves, so call before visiting.
How can I verify James Michael Mason, MD's license?
NPPES lists California license number G85713, 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 James Michael Mason, MD prescribe under Medicare Part D?
In 2024, James Michael Mason, MD had 35 Medicare Part D claims for 21 beneficiaries; the average among radiation oncology physician prescribers was 134. Part D covers Medicare prescriptions only.
What is James Michael Mason, MD's MIPS final score?
The 2023 MIPS final score is 99.1 of 100, reported for the practice group. 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.