Tony S. Chang, MD
Internal Medicine Physician · Madison, WI
Tony S. Chang, MD is an internal medicine physician with a practice address in Madison, Wisconsin, and NPI 1831166990, issued on Mar 7, 2006. Check the license (Wisconsin 42048, as entered in NPPES) on the Wisconsin Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Tony S. Chang
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 42048 WI
Self-reported in NPPES; status is on the state search - Practice location
- 20 S Park St, Madison, WI 53715
- Phone
- (608) 287-2440
- Enumerated
- Mar 7, 2006
- Record last updated
- Jan 4, 2021 (not updated in 5 years: call before relying on the address or phone)
- Fax
- (608) 287-2438
- Medicare enrollment
- Enrolled (PECOS I20100609000827); accepts Medicare assignment
- Medical or professional school
- University Of Wisconsin School Of Medicine, 1995
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 2,078 in Wisconsin → Look up another NPI →
Also registered at 20 S Park St
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Tony S. Chang in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWisconsin Medical Examining Board
Search for license 42048Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.5 times the Medicare Part D claims of the average internal medicine physician in 2024
7,967 Medicare Part D claims for 470 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 14% of claims. 250 claims were for opioids.
Most prescribed
- Atorvastatin Calcium565 claims
- Amlodipine Besylate358 claims
- Lisinopril295 claims
- Eliquis264 claims
- Omeprazole218 claims
- Losartan Potassium214 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through one group practice
- University OF Wisconsin Medical Foundation IncMadison, WI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Tony S. Chang among 2,078 internal medicine physician records in Wisconsin
Tony S. Chang, MD is one of 2,078 internal medicine physician records with a practice address in Wisconsin. 70% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 9% of them.
- NPI issued2006 · 9% of these records are older, 46% newer
- In a Medicare fileYes · 70% of these records are
- In the CMS Doctors and Clinicians fileYes · 53% of these records are
- Graduated1995 · median 2002 among the 1,098 with a school on file
- Record last updated2021 · 55% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a Wisconsin practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
417 internal medicine physician records list a practice address in Madison
They are 417 of the 15,014 NPPES records with a practice address in Madison, and 2,078 internal medicine physician records in Wisconsin.
All 2,078 in Wisconsin → Every provider in Madison → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Thomas Bugliosi, M.D.Madison, WI 537151629055124
- Rebecca Byers, MDMadison, WI 537151568439248
- Heather Childers-Okas, DOMadison, WI 537151093782765
- Richard Day, MDMadison, WI 537151972570653
- Elizabeth George, MDMadison, WI 537151255308409
- Jeremy Jaskunas, MDMadison, WI 537151568438414
- Frank Kilpatrick, MDMadison, WI 537151154397172
- Ray Kimura, MDMadison, WI 537151184690125
Common questions
What is Tony S. Chang, MD's NPI number?
Tony S. Chang, MD's National Provider Identifier (NPI) is 1831166990, issued on Mar 7, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Tony S. Chang, MD located?
The NPPES record lists a practice address at 20 S Park St, Madison, WI, 53715. Phone: (608) 287-2440. Providers update this record themselves, so call before visiting.
How can I verify Tony S. Chang, MD's license?
NPPES lists Wisconsin license number 42048, as entered by the provider. Search the Wisconsin Medical Examining Board at https://dsps.wi.gov/Pages/BoardsCouncils/MEB/Default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Tony S. Chang, MD prescribe under Medicare Part D?
In 2024, Tony S. Chang, MD had 7,967 Medicare Part D claims for 470 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.