NPPES file of Aug 9, 2026

Jacob C. Holzer, M.D.

Psychiatry Physician · Westborough, MA

Jacob C. Holzer, M.D. is a psychiatry physician with a practice address in Westborough, Massachusetts, and NPI 1144235433, issued on Jul 29, 2006. Check the license (Massachusetts 74258, as entered in NPPES) on the Massachusetts Board of Registration in Medicine; the Medicare figures below come from public CMS files.

Record from CMS NPPES, file of Aug 9, 2026 · Medicare files 2024 · method · Verify with CMS →

NPPES recordNPPES file of Aug 9, 2026
1144235433
Name
Jacob C. Holzer
Credential
M.D.
Primary taxonomy
Psychiatry Physician 2084P0800X
License number
74258 MA
Self-reported in NPPES; status is on the state search
Practice location
Westborough State Hospital, Westborough, MA 01581
Phone
(508) 616-2525
Enumerated
Jul 29, 2006
Record last updated
Jul 8, 2007 (not updated in 19 years: call before relying on the address or phone)
Medicare enrollment
Enrolled (PECOS I20040330000985); accepts Medicare assignment
Medical or professional school
Tufts University School Of Medicine, 1986
Telehealth
Offers telehealth (CMS)
Entity
Type 1 · individual
Public record from CMS NPPES (open it on the CMS NPI Registry). Enrollment, assignment, school and telehealth: CMS Doctors and Clinicians file, Aug 2026. A record is not a license: verify it with the state board.
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Also registered at Westborough State Hospital

A shared address usually means a shared clinic or building; it does not show who employs whom.

  1. Laurie Adelstein, OTROccupational Therapist1295887693
  2. Terrie Burda, PSY.D.Forensic Psychologist1245395888
  3. Kerry Korba, RN, MSN, CPNPPediatric Nurse Practitioner1851456388
  4. Ewa Mamber, O.D.Optometrist1649458209
  5. Robert Mulvey, M.D.Psychiatry Physician1578628335
  6. Diane Trikakis, OTRLOccupational Therapist1720138944

Verify Jacob C. Holzer in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersMassachusetts Board of Registration in Medicine
    Search for license 74258
    Check the board
  3. 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
  4. 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
  5. 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Open the Massachusetts license search

PlainDoctor does not match the HHS-OIG exclusion list to individual records: most entries carry no NPI. Search the OIG exclusion list by name.

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96% fewer Medicare Part D claims than the average psychiatry physician in 2024

44 Medicare Part D claims for 18 beneficiaries, against an average of 1,000 among the 35,054 providers of this specialty who prescribed in Part D.

  1. Jacob Holzer44
  2. Specialty average1,000

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 2 group practices

  1. Massachusetts General Physicians Organization IncBoston, MA
  2. The Mclean Hospital CorporationBelmont, MA

Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).

16 psychiatry physician records list a practice address in Westborough

They are 16 of the 565 NPPES records with a practice address in Westborough, and 2,736 psychiatry physician records in Massachusetts.

Other psychiatry physician records in Massachusetts

  1. Karen Abdool, M.D., PH.DLynn, MA1942472824
  2. Harmony Abejuela, M.D.Quincy, MA1316259492
  3. Marielle Abell, PAAmherst, MA1275644072
  4. Steven Ablon, MDBoston, MA1083604839
  5. Keith Ablow, M.D.Newbury, MA1245423615
  6. Yousef Abou-Allaban, MDWalpole, MA1922040666
  7. Habiba Abozeid, MDBoston, MA1689408346
  8. Margarita Abramovich, MDPittsfield, MA1154883239
  9. Howard Abrams, MDSalem, MA1821102773
  10. David Abramson, MDCambridge, MA1376679787

Common questions

What is Jacob C. Holzer, M.D.'s NPI number?

Jacob C. Holzer, M.D.'s National Provider Identifier (NPI) is 1144235433, issued on Jul 29, 2006. An NPI identifies a provider in billing; it is not a license.

Where is Jacob C. Holzer, M.D. located?

The NPPES record lists a practice address at Westborough State Hospital, Westborough, MA, 01581. Phone: (508) 616-2525. Providers update this record themselves, so call before visiting.

How can I verify Jacob C. Holzer, M.D.'s license?

NPPES lists Massachusetts license number 74258, as entered by the provider. Search the Massachusetts Board of Registration in Medicine at https://findmydoctor.mass.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.

How much does Jacob C. Holzer, M.D. prescribe under Medicare Part D?

In 2024, Jacob C. Holzer, M.D. had 44 Medicare Part D claims for 18 beneficiaries; the average among psychiatry physician prescribers was 1,000. 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.