Michael E. Mason, MD
Internal Medicine Physician · San Rafael, CA
Michael E. Mason, MD is an internal medicine physician with a practice address in San Rafael, California, and NPI 1215011200, issued on Oct 25, 2006. Check the license (California A62372, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Michael E. Mason
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A62372 CA
Self-reported in NPPES; status is on the state search - Practice location
- 99 Montecillo RD, San Rafael, CA 94903
- Phone
- (415) 444-2000
- Enumerated
- Oct 25, 2006
- Record last updated
- Dec 13, 2021 (not updated in 5 years: call before relying on the address or phone)
- Medicaid ID
- 00A623720 CA
- Medicare enrollment
- Enrolled (PECOS I20101111000043); accepts Medicare assignment
- Medical or professional school
- University Of California, Geffen School Of Medicine, 1995
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 99 Montecillo RD
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Michael E. Mason in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A62372Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.2 times the Medicare Part D claims of the average internal medicine physician in 2024
6,898 Medicare Part D claims for 787 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 8% of claims. 252 claims were for opioids.
Most prescribed
- Atorvastatin Calcium661 claims
- Lisinopril255 claims
- Amlodipine Besylate240 claims
- Levothyroxine Sodium204 claims
- Tamsulosin Hcl170 claims
- Famotidine164 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
- Permanente Medical Group IncVallejo, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Michael E. Mason among 17,696 internal medicine physician records in California
Michael E. Mason, MD is one of 17,696 internal medicine physician records with a practice address in California. 79% 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 5% of them.
- NPI issued2006 · 5% of these records are older, 56% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1995 · median 2004 among the 11,065 with a school on file
- Record last updated2021 · 61% 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 California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
51 internal medicine physician records list a practice address in San Rafael
They are 51 of the 3,159 NPPES records with a practice address in San Rafael, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in San Rafael → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Patricia Bauman, M.D.San Rafael, CA 949031710077482
- Bryn Duffy, MDSan Rafael, CA 949031235243775
- Jill Dunton, MDSan Rafael, CA 949031588748552
- Joseph Habis, M.D.San Rafael, CA 949031760439681
- Jeffrey Harris, MDSan Rafael, CA 949031134203136
- Alpana Kharkar, MDSan Rafael, CA 949031982788055
- Steven Killpack, MDSan Rafael, CA 949031477651149
- Alan Kneitel, MDSan Rafael, CA 949031417031584
Common questions
What is Michael E. Mason, MD's NPI number?
Michael E. Mason, MD's National Provider Identifier (NPI) is 1215011200, issued on Oct 25, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Michael E. Mason, MD located?
The NPPES record lists a practice address at 99 Montecillo RD, San Rafael, CA, 94903. Phone: (415) 444-2000. Providers update this record themselves, so call before visiting.
How can I verify Michael E. Mason, MD's license?
NPPES lists California license number A62372, 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 Michael E. Mason, MD prescribe under Medicare Part D?
In 2024, Michael E. Mason, MD had 6,898 Medicare Part D claims for 787 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.