JAMES MICHAEL MASON MD
NPI 1902955818
Radiology - Radiation Oncology in Wildomar, CA
About James Michael Mason Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
JAMES MICHAEL MASON MD (NPI 1902955818) is an individual radiation oncology provider in Wildomar, California, licensed in California (G85713) and active in the NPI registry since January 2007. He is enrolled in Medicare PECOS, maintains a secondary practice location in Riverside, and is a graduate of Wayne State University School Of Medicine (1988).
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Location 1
Other Identifiers 1
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
James Michael Mason Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
2Medicare enrollment records show James Mason reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
San Diego, CA 92123
- Reassigned Medicare billing, California enrollment
- 6 clinicians in this Medicare group
Duarte, CA 91010
- Reassigned Medicare billing, California enrollment
- 1,335 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims 6
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Physician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 92595 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Medicare Quality Performance CMS QPP · MIPS
Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
WILDOMAR, CA 92595
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 James Mason's NPI number?
The NPI number for James Mason is 1902955818. It was assigned to this individual provider in the NPPES registry on January 9, 2007.
Where is James Mason located?
James Mason practices at 36450 Inland Valley Dr, Wildomar, CA 92595. The listed phone number is (951) 696-0679.
What is James Mason's specialty?
The primary specialty registered for this NPI is Radiology, specializing in Radiation Oncology, with taxonomy code 2085R0001X.
Is James Mason enrolled in Medicare?
Yes. James Mason is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for James Mason's services?
According to the CMS Revalidation Reassignment List (October 2026 release), James Mason reassigns Medicare benefits to 2 organizations: Walter K Nahm MD Phd Inc (San Diego, CA) and City Of Hope Medical Foundation (Duarte, CA). Each 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 James Mason's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
When was this NPI record last updated?
The NPPES record for James Mason was last updated on November 13, 2020. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 5 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.