Quick answers
- Does Tony S. Chang accept Medicare assignment?
- Yes. Medicare's clinician data says Tony S. Chang accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Tony S. Chang see?
- In 2024, CMS data shows 265 Original Medicare patients and 1,230 services for Tony S. Chang. This counts Original Medicare only and measures volume, not quality.
- What is Tony S. Chang's NPI number?
- 1831166990. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Tony S. Chang, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 265 |
|---|---|
| Services billed to Medicare | 1,230 |
| Different services or procedures | 47 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- Visit complexity inherent to evaluation and management associated with medical care services that serve as the continuing focal point for all needed health care services and/or with medical care services that are part of ongoing care related to a patient's (G2211)293 services
- Insertion of needle into vein for collection of blood sample (36415)242 services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)160 services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)103 services
- Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more (99215)87 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High cholesterol75%
- High blood pressure69%
- Diabetes26%
- Arthritis23%
- Ischemic heart disease21%
- Chronic kidney disease20%
Hospitals where Tony S. Chang works
Medicare's Facility Affiliation Data lists Tony S. Chang at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- UnityPoint Health - MeriterMadison, WI · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 520089
- University of WI Hospitals & Clinics AuthorityMadison, WI · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 520098
Practice locations
Addresses where Tony S. Chang is enrolled with Medicare (CMS data updated October 2, 2026). The first 5 of 17; the Medicare profile lists all.
- 1 S Park StMadison, WI 53715 (608) 287‑2000
- 100 N Nine Mound RdVerona, WI 53593
- 1001 Nygaard StStoughton, WI 53589 (608) 877‑2660
- 1050 E BroadwayMonona, WI 53716 (608) 222‑8779
- 1121 Bellwest BlvdBelleville, WI 53508
Group practices
Medicare enrollment lists Tony S. Chang as a member of this group (CMS data updated October 2, 2026).
- University of Wisconsin Medical Foundation Inc2,553 clinicians in the group
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Madison
Clinicians with the same Medicare primary specialty in Madison, WI — not a recommendation.
Other clinicians in University of Wisconsin Medical Foundation Inc
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Wisconsin School Of Medicine |
| Graduation year | 1995 (31 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1831166990 |
| 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 October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- 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