NPPES file of Aug 9, 2026

William Aaron Markoff, M.D.

Family Medicine Physician · Santa Rosa, CA

William Aaron Markoff, M.D. is a family medicine physician with a practice address in Santa Rosa, California, and NPI 1407869167, issued on Aug 14, 2006. Check the license (California A74621, as entered in NPPES) on the Medical Board of California; 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
1407869167
Name
William Aaron Markoff
Credential
M.D.
Primary taxonomy
Family Medicine Physician 207Q00000X
License number
A74621 CA
Self-reported in NPPES; status is on the state search
Practice location
3536 Mendocino Ave Ste 300, Santa Rosa, CA 95403
Phone
(707) 544-3811
Enumerated
Aug 14, 2006
Record last updated
Nov 30, 2021 (not updated in 5 years: call before relying on the address or phone)
Fax
(707) 544-0128
Medicaid ID
1407869167 CA
Medicare enrollment
Enrolled (PECOS I20080722000782); accepts Medicare assignment
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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8 nearest family medicine physician records → All 17,133 in California → Look up another NPI →

Also registered at 3536 Mendocino Ave Ste 300

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

  1. Seema Rao, MD.Geriatric Medicine (Internal Medicine) Physician1275714495
  2. James Trapnell, M.D.Family Medicine Physician1073526729

Verify William Aaron Markoff in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersMedical Board of California
    Search for license A74621    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 California 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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2.4 times the Medicare Part D claims of the average family medicine physician in 2024

8,605 Medicare Part D claims for 812 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. Brand-name drugs were 9% of claims. 162 claims were for opioids.

  1. William Markoff8,605
  2. Specialty average3,544

Most prescribed

  1. Atorvastatin Calcium651 claims
  2. Levothyroxine Sodium462 claims
  3. Rosuvastatin Calcium348 claims
  4. Amlodipine Besylate326 claims
  5. Metformin Hcl322 claims
  6. Losartan Potassium295 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.

Industry payments in 2024: $17.44

1 payment: education; the largest payer was Pfizer Inc. The 55,478 providers of this specialty with any payment received $902.55 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.

  1. William Markoff$17.44
  2. Specialty average$902.55

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

  1. Providence Medical FoundationSanta Rosa, CA

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

William Aaron Markoff among 17,133 family medicine physician records in California

William Aaron Markoff, M.D. is one of 17,133 family medicine physician records with a practice address in California. 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 6% of them.

  • NPI issued2006 · 6% of these records are older, 59% newer
  • In a Medicare fileYes · 81% of these records are
  • In the CMS Doctors and Clinicians fileYes · 62% of these records are
  • Graduated1998 · median 2005 among the 10,652 with a school on file
  • Record last updated2021 · 58% of these records were not updated in five years or more

Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).

264 family medicine physician records list a practice address in Santa Rosa

They are 264 of the 6,884 NPPES records with a practice address in Santa Rosa, and 17,133 family medicine physician records in California.

All 17,133 in California → Every provider in Santa Rosa → Family Medicine Physician nationwide →

The 8 family medicine physician records with the nearest ZIP codes

  1. Robert Gabbay, D.O.Santa Rosa, CA 954031821028283
  2. Karen Gelphman, MDSanta Rosa, CA 954031972565703
  3. Jennifer Lee, MDSanta Rosa, CA 954031447288204
  4. Azra Mael, M.D.Santa Rosa, CA 954031477596518
  5. Patricia Mazzetti Hiserote, D.O.Santa Rosa, CA 954031821002593
  6. Neil Nathan, MDSanta Rosa, CA 954031174510788
  7. Amelia Randolph, MDSanta Rosa, CA 954031093739708
  8. Edward Rose, M.D.Santa Rosa, CA 954031750354106

Common questions

What is William Aaron Markoff, M.D.'s NPI number?

William Aaron Markoff, M.D.'s National Provider Identifier (NPI) is 1407869167, issued on Aug 14, 2006. An NPI identifies a provider in billing; it is not a license.

Where is William Aaron Markoff, M.D. located?

The NPPES record lists a practice address at 3536 Mendocino Ave Ste 300, Santa Rosa, CA, 95403. Phone: (707) 544-3811. Providers update this record themselves, so call before visiting.

How can I verify William Aaron Markoff, M.D.'s license?

NPPES lists California license number A74621, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.

How much does William Aaron Markoff, M.D. prescribe under Medicare Part D?

In 2024, William Aaron Markoff, M.D. had 8,605 Medicare Part D claims for 812 beneficiaries; the average among family medicine physician prescribers was 3,544. 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.

Written with AI tools from the named public files; every figure is computed from those files (how it is made).

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.