Robert Mah, DO
Family Medicine Physician · Fontana, CA
Robert Mah, DO is a family medicine physician with a practice address in Fontana, California, and NPI 1871876995, issued on Sep 25, 2011. Check the license (California 20A11877, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Robert Mah
- Credential
- DO
- Primary taxonomy
- Family Medicine Physician 207Q00000X
- License number
- 20A11877 CA
Self-reported in NPPES; status is on the state search - Practice location
- 9961 Sierra Ave, Fontana, CA 92335
- Phone
- (888) 750-0036
- Enumerated
- Sep 25, 2011
- Record last updated
- Dec 2, 2021 (not updated in 5 years: call before relying on the address or phone)
- Medicare enrollment
- Enrolled (PECOS I20120531000643); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest family medicine physician records → All 17,133 in California → Look up another NPI →
Also registered at 9961 Sierra Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Robert Mah in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license 20A11877Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
53% more Medicare Part D claims than the average family medicine physician in 2024
5,409 Medicare Part D claims for 823 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. Brand-name drugs were 8% of claims. 200 claims were for opioids.
Most prescribed
- Atorvastatin Calcium447 claims
- Amlodipine Besylate184 claims
- Losartan Potassium179 claims
- Lisinopril172 claims
- Simvastatin155 claims
- Levothyroxine Sodium148 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
- Southern California Permanente Medical GroupRancho Cucamonga, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Robert Mah among 17,133 family medicine physician records in California
Robert Mah, DO 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 2011, is newer than 63% of them.
- NPI issued2011 · 63% of these records are older, 34% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 62% of these records are
- Graduated2010 · 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).
198 family medicine physician records list a practice address in Fontana
They are 198 of the 3,012 NPPES records with a practice address in Fontana, and 17,133 family medicine physician records in California.
All 17,133 in California → Every provider in Fontana → Family Medicine Physician nationwide →
The 8 family medicine physician records with the nearest ZIP codes
- Frances Burke, MDFontana, CA 923351972674901
- Nathan Carlson, M.D.Fontana, CA 923351144212929
- Christine Carlson, MDFontana, CA 923351386612299
- Thawat Eosakul, M.D.Fontana, CA 923351811904519
- Diane Hom, MDFontana, CA 923351821169707
- Anissa Lacount, MDFontana, CA 923351609854397
- Rubin Lin, D.O.Fontana, CA 923351679678916
- Lannie Moy, PA-CFontana, CA 923351922037738
Common questions
What is Robert Mah, DO's NPI number?
Robert Mah, DO's National Provider Identifier (NPI) is 1871876995, issued on Sep 25, 2011. An NPI identifies a provider in billing; it is not a license.
Where is Robert Mah, DO located?
The NPPES record lists a practice address at 9961 Sierra Ave, Fontana, CA, 92335. Phone: (888) 750-0036. Providers update this record themselves, so call before visiting.
How can I verify Robert Mah, DO's license?
NPPES lists California license number 20A11877, 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 Robert Mah, DO prescribe under Medicare Part D?
In 2024, Robert Mah, DO had 5,409 Medicare Part D claims for 823 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.
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.