Quick answers
- Which hospitals does Thom S. Thomassen work at?
- Medicare's official clinician data lists Thom S. Thomassen at 1 hospital: Mercy Health System Corp. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Thom S. Thomassen see patients?
- Medicare's clinician data lists 1 practice location in Janesville, WI. Call before your visit to confirm the address.
- What is Thom S. Thomassen's specialty?
- Medicare lists Ophthalmology as the primary specialty.
- Does Thom S. Thomassen accept Medicare assignment?
- Yes. Medicare's clinician data says Thom S. Thomassen accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Thom S. Thomassen?
- (608) 756-7100, as listed in official Medicare / NPI Registry data.
- What is Thom S. Thomassen's NPI number?
- 1407903180. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Thom S. Thomassen works
Medicare's Facility Affiliation Data lists Thom S. Thomassen at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Mercy Health System CorpJanesville, WI · Acute Care Hospital · CCN 520066
Practice locations
Addresses where Thom S. Thomassen is enrolled with Medicare (CMS data updated 2026-10-02).
- 3524 E Milwaukee StJanesville, WI 53546 (608) 756‑7100
Group practices
Medicare enrollment lists Thom S. Thomassen as a member of this group (CMS data updated 2026-10-02).
- Mercy Health System Corporation753 clinicians in the group
Specialties
- Ophthalmologyprimary
Other ophthalmologists in Janesville
Clinicians with the same Medicare primary specialty in Janesville, WI — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Duke University School Of Medicine |
| Graduation year | 1977 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1407903180 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians