Gerald J. Kallas, M.D.
Internal Medicine Physician · Oconomowoc, WI
Gerald J. Kallas, M.D. is an internal medicine physician with a practice address in Oconomowoc, Wisconsin, and NPI 1770959462, issued on Aug 17, 2015. Check the license (Wisconsin 14655-20, as entered in NPPES) on the Wisconsin Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Gerald J. Kallas
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 14655-20 WI
Self-reported in NPPES; status is on the state search - Practice location
- 1437 N Summit Ave, Oconomowoc, WI 53066
- Phone
- (414) 322-1434
- Enumerated
- Aug 17, 2015
- Record last updated
- Aug 17, 2015 (not updated in 11 years: call before relying on the address or phone)
- Medicaid ID
- 14655-20 WI
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 2,078 in Wisconsin → Look up another NPI →
Verify Gerald J. Kallas in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWisconsin Medical Examining Board
Search for license 14655-20Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
95% fewer Medicare Part D claims than the average internal medicine physician in 2024
157 Medicare Part D claims for 11 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
Most prescribed
- Levothyroxine Sodium14 claims
- Furosemide12 claims
- Potassium Chloride12 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.
Gerald J. Kallas among 2,078 internal medicine physician records in Wisconsin
Gerald J. Kallas, M.D. 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 2015, is newer than 73% of them.
- NPI issued2015 · 73% of these records are older, 25% newer
- In a Medicare fileYes · 70% of these records are
- In the CMS Doctors and Clinicians fileNo · 53% of these records are
- Record last updated2015 · 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).
12 internal medicine physician records list a practice address in Oconomowoc
They are 12 of the 506 NPPES records with a practice address in Oconomowoc, and 2,078 internal medicine physician records in Wisconsin.
All 2,078 in Wisconsin → Every provider in Oconomowoc → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Tulay Aksoy, MDSummit, WI 530661245485697
- Brenda Boschek, M.D.Oconomowoc, WI 530661154393833
- Julius BreyerOconomowoc, WI 530661760621809
- Dan Cleary, MDOconomowoc, WI 530661972615136
- Eric Conradson, M.D.Oconomowoc, WI 530661518976232
- William Cooper, MDOconomowoc, WI 530661023078037
- Pravin Gupta, M.D.Summit, WI 530661124132188
- Brett Linzer, M.D.Oconomowoc, WI 530661083686653
Common questions
What is Gerald J. Kallas, M.D.'s NPI number?
Gerald J. Kallas, M.D.'s National Provider Identifier (NPI) is 1770959462, issued on Aug 17, 2015. An NPI identifies a provider in billing; it is not a license.
Where is Gerald J. Kallas, M.D. located?
The NPPES record lists a practice address at 1437 N Summit Ave, Oconomowoc, WI, 53066. Phone: (414) 322-1434. Providers update this record themselves, so call before visiting.
How can I verify Gerald J. Kallas, M.D.'s license?
NPPES lists Wisconsin license number 14655-20, 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 Gerald J. Kallas, M.D. prescribe under Medicare Part D?
In 2024, Gerald J. Kallas, M.D. had 157 Medicare Part D claims for 11 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.