THOMAS NEIL O'CALLAGHAN MD
NPI 1265926331
Internal Medicine in Ann Arbor, MI
About Thomas Neil O'callaghan Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
THOMAS NEIL O'CALLAGHAN MD (NPI 1265926331) is an individual internal medicine provider in Ann Arbor, Michigan, licensed in Michigan (4301507148) and active in the NPI registry since June 2018. He is enrolled in Medicare PECOS, is affiliated with University Of Michigan Health System, and is a graduate of University Of Michigan Medical School (2022).
NPPES Registry Identity
Specialties & Licenses
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
Thomas Neil O'callaghan 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
3Medicare enrollment records show Thomas O'callaghan reassigns Medicare billing to 3 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Ann Arbor, MI 48109
- Reassigned Medicare billing, Michigan enrollment
- 2,377 clinicians in this Medicare group
Ann Arbor, MI 48105
- Reassigned Medicare billing, Michigan enrollment
- 1,480 clinicians in this Medicare group
Chelsea, MI 48118
- Reassigned Medicare billing, Michigan enrollment
- 147 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
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.
Hospital Affiliations CMS Care Compare 2
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
University Of Michigan Health System
Acute Care Hospitals · Ann Arbor, MIChelsea Hospital
Acute Care Hospitals · Chelsea, MIPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 48109 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.
ANN ARBOR, MI 48109
ANN ARBOR, MI 48109
ANN ARBOR, MI 48109
ANN ARBOR, MI 48109
ANN ARBOR, MI 48109
ANN ARBOR, MI 48109
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 Thomas O'callaghan's NPI number?
The NPI number for Thomas O'callaghan is 1265926331. It was assigned to this individual provider in the NPPES registry on June 21, 2018.
Where is Thomas O'callaghan located?
Thomas O'callaghan practices at 1500 E Medical Center Dr, Ann Arbor, MI 48109. The listed phone number is (734) 936-4000.
What is Thomas O'callaghan's specialty?
The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.
Is Thomas O'callaghan enrolled in Medicare?
Yes. Thomas O'callaghan 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 Thomas O'callaghan's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Thomas O'callaghan reassigns Medicare benefits to 3 organizations: Regents Of The University Of Michigan (Ann Arbor, MI), Iha Health Services Corporation (Ann Arbor, MI) and Chelsea Community Hospital (Chelsea, MI). 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 Thomas O'callaghan's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Thomas O'callaghan accept?
Health plans from Ambetter Health, Ambetter from Buckeye Health Plan, Ambetter from Meridian, Blue Care Network of Michigan and Blue Cross Blue Shield of Michigan Mutual Insurance Company and 1 other insurer list Thomas O'callaghan 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.
Is Thomas O'callaghan affiliated with any hospitals?
According to CMS data, Thomas O'callaghan is affiliated with University Of Michigan Health System and Chelsea Hospital.
When was this NPI record last updated?
The NPPES record for Thomas O'callaghan was last updated on July 25, 2022. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 4 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.
# Thomas Neil O'callaghan, MD · NPI 1265926331
Internal Medicine physician in Ann Arbor, Michigan. Individual provider, active in the CMS NPPES registry since June 21, 2018.
## Identity
- **NPI:** 1265926331 (Entity type: Individual)
- **Enumerated:** June 21, 2018
- **Primary specialty:** Internal Medicine · taxonomy 207R00000X
- **State license:** 4301507148 (Michigan)
- **Sole proprietor:** No
## Practice location
- **Address:** 1500 E MEDICAL CENTER DR, Ann Arbor, MI 48109-5000
- **Phone:** (734) 936-4000
## 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:** 3 organizations under Medicare reassignment (form CMS-855R): Regents Of The University Of Michigan (NPI 1003848144, Ann Arbor, MI); Iha Health Services Corporation (NPI 1013194307, Ann Arbor, MI); Chelsea Community Hospital (NPI 1912947409, Chelsea, MI) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** University Of Michigan Medical School, class of 2022
## Record status
- **NPPES last updated:** July 25, 2022
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Source: [NPI Profile](https://npiprofile.com/npi/1265926331) · Data from the CMS NPPES public registry.