NPI registry status
Active
2026 NPPES data Nephrology Physician NPI 1851450456 MD
Verify on CMS → Jason Mak, MD
Nephrology Physician in Fontana, California.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 10,569 in Nephrology Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
178
Medicare Part D claims · 86 beneficiaries · Nephrology Physician avg: 1K
Generic prescribing
93%
generic claims · 7% brand-name · higher generic rates reduce patient out-of-pocket costs
Source: CMS Medicare Part D Prescriber Public Use File, 2023
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
Jason Mak, MD filed 178 Medicare Part D claims in 2023 as a Nephrology Physician in Fontana, California, prescribing 93% generic.
- 178
- Part D claims, 2023
- 93%
- generic prescribing
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Jason Mak, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
178 35th percentile higher than 35% of 1,370,886 prescribers
Each bar is a band; taller bars hold more prescribers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source CMS Medicare Part D Prescriber Public Use File · 2023
◑
Board-eligible specialty (heuristic, not verified)
Jason Mak, MD practices in an ABMS-board-eligible specialty but we don't have enough CMS-participation signals to confirm active board-certified status. Consult CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Jason Mak, MD?
Quality data not reportedPrimary specialty
Nephrology Physician
Medicare Part D claims
178 88% vs specialty avg
Specialty distribution in California
How Nephrology Physician compares to other specialties among California providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Nephrology Physician. Verify directly:
How MIPS and board certification work
The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.
Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).
Jason Mak, MD appears in the CMS NPPES registry as a Nephrology Physician provider holding MD credentials at 9961 SIERRA AVE, Fontana, CA, 92335, with a listed phone of (909) 427-3910. NPI 1851450456 was issued on 12/08/2006.
Medicare Part D records for calendar year 2023 show 178 prescription claims written by this provider, covering 86 Medicare beneficiaries and totaling roughly $9K in drug spend, split 7% brand-name and 93% generic by claim count.
Nephrology Physician is a mid-sized specialty nationwide, with 10,569 enrolled providers across 55 states and an average of 1,454 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline.
Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist, always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.
Practice Address
Provider Details
| NPI | 1851450456 |
|---|---|
| Specialty | Nephrology Physician |
| Credentials | MD |
| Gender | Male |
| NPI Issued | 12/08/2006 |
License & disciplinary context - California MBC 2023 annual report
Aggregate state board data only, NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~150K California medical licensees in 2023 - they are NOT specific to Jason Mak, MD. To verify Jason Mak, MD's current license status, search the MBC public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
576
Total board actions, California 2023
Across 556 cases
3.84
Actions per 1,000 licensees
California statewide rate
probation
Most common action type
186 cases
MBC publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the California disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Brand vs generic prescribing mix · Generic-heavy
Jason Mak, MD - brand share 7.0%
Nephrology Physician average
7% brand-name claims vs 93% generic, on 178 2023 Medicare Part D claims.
The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
178
Total Claims
$9K
Total Drug Cost
86
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 548
- Total Day Supply
- 16,309
- Brand vs Generic
- 7% brand / 93% generic
- Brand Drug Cost
- $1K
- Generic Drug Cost
- $8K
Patient Demographics
- Average Patient Age
- 74.4 years
- Avg HCC Risk Score
- 4.44
- Gender Split
- 47% female / 53% male
- Age Distribution
- <65: 11, 65-74: 33, 75-84: 28, 85+: 14
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Jason Mak, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Amlodipine Besylate
Amlodipine Besylate
29 claims
- Hydralazine Hcl
Hydralazine Hcl
14 claims
- Metoprolol Tartrate
Metoprolol Tartrate
14 claims
- Losartan Potassium
Losartan Potassium
12 claims
- Sevelamer Carbonate
Sevelamer Carbonate
12 claims
- Furosemide 11
Furosemide
11 claims
| Drug | Claims |
|---|---|
| Amlodipine Besylate | 29 |
| Hydralazine Hcl | 14 |
| Metoprolol Tartrate | 14 |
| Losartan Potassium | 12 |
| Sevelamer Carbonate | 12 |
| Furosemide | 11 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Nephrology Physician Overview
How Jason Mak, MD fits within the Nephrology Physician landscape nationally.
10,569
Nephrology Physician Providers in US
55
States with Nephrology Physician
1,454
Avg Claims per Provider
Jason Mak, MD's 178 claims are below the specialty average of 1,454.
Nearby Nephrology Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Mak.
Dr. Antoine Abcar
MD
Los Angeles, CA
Dr. Basmah Abdalla
M.D.
Los Angeles, CA
Dr. Omaran Abdeen
M.D.
Mission Hills, CA
Dr. Anas Abou-Ismail
MD
Palm Springs, CA
Dr. Sreedhar Adapa
M.D.
Visalia, CA
Compare Nephrology Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the California medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Nephrology Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
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Frequently Asked Questions
What is Jason Mak, MD's specialty? ▼
Jason Mak, MD specializes in Nephrology Physician and practices in Fontana, California. Credentials: MD.
How much does Jason Mak, MD prescribe under Medicare Part D? ▼
In 2023, Jason Mak, MD wrote 178 Medicare Part D claims totaling $9K in drug costs for 86 beneficiaries.
Where is Jason Mak, MD located? ▼
Jason Mak, MD is located at 9961 SIERRA AVE, Fontana, CA, 92335. Phone: (909) 427-3910.
What is Jason Mak, MD's NPI number? ▼
Jason Mak, MD's National Provider Identifier (NPI) is 1851450456, issued on 12/08/2006.
Does Jason Mak, MD prescribe more brand-name or generic drugs? ▼
Jason Mak, MD's prescribing is 7% brand-name and 93% generic drugs by claim count, with $1K in brand drug costs.
How many Nephrology Physician providers are there in the US? ▼
There are 10,569 Nephrology Physician providers across 55 states in the US. The average Nephrology Physician provider writes 1,454 Medicare Part D claims per year.
What drugs does Jason Mak, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Jason Mak, MD's most frequently prescribed drugs include Amlodipine Besylate, Hydralazine Hcl, Metoprolol Tartrate. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Jason Mak, MD accept Medicare? ▼
Jason Mak, MD appears in CMS Medicare data with 178 Part D claims and 86 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Jason Mak, MD's credentials? ▼
Jason Mak, MD's NPI is 1851450456 with credentials MD. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.
Data Sources
View source datasets and methodology notes
- Provider Directory
- CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
- Specialty Classification
- NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
- Prescribing Data
- CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
- Limitations
- Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.
See our complete data methodology for details on how we collect and process government data.
Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).
Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology
Compiled from official public sources by the PlainDoctor editorial team.
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.