JOHN K BYUN MD
NPI 1528487089
Radiology - Radiation Oncology in Stony Brook, NY
About John K Byun Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
JOHN K BYUN MD (NPI 1528487089) is an individual radiation oncology provider in Stony Brook, New York, licensed in New York (345605) and active in the NPI registry since April 2014. He is enrolled in Medicare PECOS, maintains 4 additional practice locations, and is a graduate of Other (2014).
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Locations 4
Accepted Insurance
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
John K Byun 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
6Medicare enrollment records show John Byun reassigns Medicare billing to 6 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Northampton, MA 01060
- Reassigned Medicare billing, Massachusetts enrollment
- 539 clinicians in this Medicare group
Boston, MA 02114
- Reassigned Medicare billing, Massachusetts enrollment
- 6,234 clinicians in this Medicare group
Boston, MA 02114
- Reassigned Medicare billing, Massachusetts enrollment
- 6,360 clinicians in this Medicare group
Grass Valley, CA 95945
- Reassigned Medicare billing, California enrollment
- 9 clinicians in this Medicare group
Pleasanton, CA 94588
- Reassigned Medicare billing, California enrollment
- 4,258 clinicians in this Medicare group
Palo Alto, CA 94304
- Reassigned Medicare billing, California enrollment
- 3,617 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 11
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 11794 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
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.
STONY BROOK, NY 11794
STONY BROOK, NY 11794
STONY BROOK, NY 11794
STONY BROOK, NY 11794
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 John Byun's NPI number?
The NPI number for John Byun is 1528487089. It was assigned to this individual provider in the NPPES registry on April 14, 2014.
Where is John Byun located?
John Byun practices at 101 Nicolls Rd, Stony Brook, NY 11794. The listed phone number is (631) 444-2325.
What is John Byun's specialty?
The primary specialty registered for this NPI is Radiology, specializing in Radiation Oncology, with taxonomy code 2085R0001X.
Is John Byun enrolled in Medicare?
Yes. John Byun 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 John Byun's services?
According to the CMS Revalidation Reassignment List (October 2026 release), John Byun reassigns Medicare benefits to 6 organizations: Mass General Brigham Medical Group Western Massachusetts Inc (Northampton, MA), The General Hospital Corporation (Boston, MA), Massachusetts General Physicians Organization Inc (Boston, MA), Grass Valley Radiation Oncology (Grass Valley, CA), Stanford Health Care (Pleasanton, CA) and 1 more organization, listed in the Medicare section above. 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 John Byun's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does John Byun accept?
Health plans from Taro Health list John Byun as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.
When was this NPI record last updated?
The NPPES record for John Byun was last updated on August 11, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 2 months 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.
# John K Byun, MD · NPI 1528487089
Radiation Oncology physician in Stony Brook, New York. Individual provider, active in the CMS NPPES registry since April 14, 2014.
## Identity
- **NPI:** 1528487089 (Entity type: Individual)
- **Enumerated:** April 14, 2014
- **Primary specialty:** Radiology - Radiation Oncology · taxonomy 2085R0001X
- **State license:** 345605 (New York)
- **Sole proprietor:** No
## Practice location
- **Address:** 101 NICOLLS RD, Stony Brook, NY 11794-0001
- **Phone:** (631) 444-2325
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 6 organizations under Medicare reassignment (form CMS-855R): Mass General Brigham Medical Group Western Massachusetts Inc (NPI 1295787919, Northampton, MA); The General Hospital Corporation (NPI 1023049236, Boston, MA); Massachusetts General Physicians Organization Inc (NPI 1801874573, Boston, MA); Grass Valley Radiation Oncology (NPI 1649895194, Grass Valley, CA); Stanford Health Care (NPI 1124561758, Pleasanton, CA); and 1 more · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Other, class of 2014
## Record status
- **NPPES last updated:** August 11, 2026
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Source: [NPI Profile](https://npiprofile.com/npi/1528487089) · Data from the CMS NPPES public registry.