William P. Mustas, P.A.
Physician Assistant · Waukesha, WI
William P. Mustas, P.A. is a physician assistant with a practice address in Waukesha, Wisconsin, and NPI 1629080932, issued on Aug 13, 2006. Check the license (Wisconsin 1307, as entered in NPPES) with the Wisconsin board that licenses this profession; the Medicare figures below come from public CMS files.
- Name
- William P. Mustas
- Credential
- P.A.
- Primary taxonomy
- Physician Assistant 363A00000X
- License number
- 1307 WI
Self-reported in NPPES; status is on the state search - Practice location
- 1111 Delafield St Ste 215, Waukesha, WI 53188
- Phone
- (262) 542-0074
- Enumerated
- Aug 13, 2006
- Record last updated
- Sep 18, 2024
- Fax
- (262) 542-2803
- Medicare enrollment
- Enrolled (PECOS I20250212001475); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest physician assistant records → All 3,475 in Wisconsin → Look up another NPI →
Also registered at 1111 Delafield St Ste 215
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Megan RothFamily Nurse Practitioner1952739351
Verify William P. Mustas in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWhich Wisconsin board licenses this profession
Search for license 1307Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
24% fewer Medicare Part D claims than the average physician assistant in 2024
628 Medicare Part D claims for 230 beneficiaries, against an average of 830 among the 101,058 providers of this specialty who prescribed in Part D. 20 claims were for opioids.
Most prescribed
- Tamsulosin Hcl183 claims
- Myrbetriq61 claims
- Oxybutynin Chloride Er47 claims
- Gemtesa45 claims
- Ciprofloxacin Hcl39 claims
- Nitrofurantoin Mono-Macro29 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.
The practice group's MIPS final score for 2023 (Medicare payment program): 82.4 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023, group reporting; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $603.70
30 payments; by number, the most common kind was food and beverage; the largest payer was Sumitomo Pharma America, Inc. The 64,719 providers of this specialty with any payment received $841.65 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- Los Alamos Physician Practices LLCEspanola, NM
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
William P. Mustas among 3,475 physician assistant records in Wisconsin
William P. Mustas, P.A. is one of 3,475 physician assistant records with a practice address in Wisconsin. 81% 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 4% of them.
- NPI issued2006 · 4% of these records are older, 76% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 72% of these records are
- Graduated2000 · median 2016 among the 2,491 with a school on file
- Record last updated2024 · 38% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 363A00000X and a Wisconsin practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
89 physician assistant records list a practice address in Waukesha
They are 89 of the 2,814 NPPES records with a practice address in Waukesha, and 3,475 physician assistant records in Wisconsin.
All 3,475 in Wisconsin → Every provider in Waukesha → Physician Assistant nationwide →
The 8 physician assistant records with the nearest ZIP codes
- Rachel Anderson, PA-CWaukesha, WI 531881497983092
- Claire Benishek, PACWaukesha, WI 531881629332101
- Catherine Bril, PAWaukesha, WI 531881508828328
- Sharon De Vries, P.A.Waukesha, WI 531881972528677
- Denise Dhein, P.A.Waukesha, WI 531881477697324
- Elizabeth Kehl, PAWaukesha, WI 531881457372021
- Vasavi Kumar, PAWaukesha, WI 531881063408334
- Sarah Nowak, P.A.Waukesha, WI 531881730166026
Common questions
What is William P. Mustas, P.A.'s NPI number?
William P. Mustas, P.A.'s National Provider Identifier (NPI) is 1629080932, issued on Aug 13, 2006. An NPI identifies a provider in billing; it is not a license.
Where is William P. Mustas, P.A. located?
The NPPES record lists a practice address at 1111 Delafield St Ste 215, Waukesha, WI, 53188. Phone: (262) 542-0074. Providers update this record themselves, so call before visiting.
How can I verify William P. Mustas, P.A.'s license?
NPPES lists Wisconsin license number 1307, as entered by the provider. Search the Wisconsin board that licenses this profession; the NPPES record confirms identity only.
How much does William P. Mustas, P.A. prescribe under Medicare Part D?
In 2024, William P. Mustas, P.A. had 628 Medicare Part D claims for 230 beneficiaries; the average among physician assistant prescribers was 830. Part D covers Medicare prescriptions only.
What is William P. Mustas, P.A.'s MIPS final score?
The 2023 MIPS final score is 82.4 of 100, reported for the practice group. The average among 454,083 clinicians with a measured score was 83.5.
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.