NPI registry status
Active
2026 NPPES data Sports Medicine (Internal Medicine) Physician NPI 1801921218 M.D.
Verify on CMS → Harris Masket, M.D.
Sports Medicine (Internal Medicine) Physician in Mill Valley, 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 299 in Sports Medicine (Internal Medicine) 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
16
Medicare Part D claims · Sports Medicine (Internal Medicine) Physician avg: 1K
Industry payments
$42.87
1 payments · CMS Open Payments (Sunshine Act)
What the federal data shows
Harris Masket, M.D. filed 16 Medicare Part D claims in 2024 as a Sports Medicine (Internal Medicine) Physician in Mill Valley, California.
- 16
- Part D claims, 2024
- $42.87
- industry payments (Sunshine Act)
- ≥0th
- pct by Part D claim volume (lower-bound band)
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.
Federal trust snapshot
What official records show about Harris Masket, M.D.
Federal records show an active NPI with Medicare Part D prescribing activity — verifiable registry data, not a proprietary rating.
- Verified
NPI registry status
Active listing in the CMS National Provider Identifier Registry (NPI 1801921218), first enumerated 02/23/2007.
Source: CMS NPPES
- Reported
Medicare Part D participation
Filed 16 Medicare Part D prescription claims in the 2023 CMS public use file — indicates active Medicare prescribing participation.
Source: CMS Part D Prescriber PUF
- Reported
Board certification signal
Practices in an ABMS-board-eligible specialty; board certification not confirmed in federal records.
- Reported
Industry payment transparency
$42.87 in reported industry payments (1 transfers) in 2024 under the federal Sunshine Act — disclosed transfers of value, not a quality rating.
Source: CMS Open Payments
- State context
State board disciplinary context
California statewide board action statistics are published annually — these figures describe aggregate state activity, not Harris Masket, M.D.'s individual license status. Verify directly with the state medical board.
Source: Medical Board of California annual report FY 2022-23
- Not in federal data
Individual sanction lookup
PlainDoctor does not publish per-provider disciplinary determinations. Confirm current license and any individual actions through the state medical board or FSMB verification service.
Source: State medical board / FSMB
This trust snapshot summarizes only what appears in federal CMS/NPPES public records. It is not a composite score, star rating, patient review, or clinical recommendation. PlainDoctor never fabricates reviews or AggregateRating schema.
Compare Masket with other Sports Medicine (Internal Medicine) Physician providers
Same primary specialty, same federal CMS NPPES roster.
Also enrolled in California
- Dr. Cesar Abdul-Massih, MD Rancho Mirage, CA
- Dr. Aye Aung, MD Santa Clara, CA
- Dr. Meredith Bean, MD Oakland, CA
- Dr. Phillip Bland, MD Los Angeles, CA
- Laura Breckenridge, NP San Bruno, CA
- Dr. Anna Buehler, MD San Francisco, CA
Other specialties in Mill Valley: Marriage & Family Therapist (75) · Physical Therapist (44) · Acupuncturist (40) · Pharmacist (34)
CMS NPPES provider registry desk
NPI 1801921218 · Sports Medicine (Internal Medicine) Physician
NPI-10 · ENUM-MID · TAX-TRACE · RX-TRACE · BOOK-THIN · PHOTO-ENUM
- NPI-10 1801921218
- ENUM-MID 2007
- TAX-TRACE 299
- RX-TRACE 16
- BOOK-THIN 49 in California
- PHOTO-ENUM Kevin Eerkes, M.D. · 2007
Harris Masket, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2024, across all CMS prescribers nationally
16 ≥ 0th percentile 0% of 1,416,883 prescribers are in lower value bands
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.
The percentile is a conservative 100-claim band: it counts only prescribers in lower claim-volume bands. Medicare Part D claim volume is activity context, not a quality measure or recommendation. See methodology § corpus placement.
Source CMS Medicare Part D Prescriber Public Use File · 2024
◑
Board-eligible specialty (heuristic, not verified)
Harris Masket, M.D. 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 Harris Masket, M.D.?
Quality data not reportedPrimary specialty
Sports Medicine (Internal Medicine) Physician
Medicare Part D claims
16 99% vs specialty avg
Specialty distribution in California
How Sports Medicine (Internal Medicine) 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 Sports Medicine (Internal Medicine) 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).
Practice Address
Provider Details
| NPI | 1801921218 |
|---|---|
| Specialty | Sports Medicine (Internal Medicine) Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 02/23/2007 |
Industry payments received (2024) - CMS Open Payments transparency data
The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for Harris Masket, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$43
Largest payer
Cleerly, Inc.
Most common payment type
Food and Beverage
Industry payments are not necessarily indicators of bias, they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.
License & disciplinary context - California Medical Board of California, FY 2022-23
Aggregate state board data only, NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across 148,769 California physician licenses in effect in FY 2022-23 - they are NOT specific to Harris Masket, M.D.. To verify Harris Masket, M.D.'s current license status, use the state board's own license search (see California license lookup), or the Federation of State Medical Boards (FSMB) verification service.
374
Administrative board actions, California FY 2022-23
2.51
Actions per 1,000 physician licenses in effect
California statewide rate
Probation
Most common action type
148 actions
Source: Medical Board of California Annual Report 2022-2023, page 18 (licenses in effect: page 12). Full breakdown by action type on the California discipline page.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2024.
16
Total Claims
$959
Total Drug Cost
N/A
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 28.6
- Total Day Supply
- 775
- Generic Drug Cost
- $949
Patient Demographics
- Average Patient Age
- 77.0 years
- Avg HCC Risk Score
- 1.16
More Sports Medicine (Internal Medicine) Physician in CA →
All providers in California →
Compare specialties →
Sports Medicine (Internal Medicine) Physician Overview
How Harris Masket, M.D. fits within the Sports Medicine (Internal Medicine) Physician landscape nationally.
299
Sports Medicine (Internal Medicine) Physician Providers in US
44
States with Sports Medicine (Internal Medicine) Physician
1,220
Avg Claims per Provider
Harris Masket, M.D.'s 16 claims are below the specialty average of 1,220.
Nationwide Sports Medicine (Internal Medicine) Physician peers with similar MIPS or enrollment year
Two federal-record peer sets for Masket, both outside California so the neighborhoods are not geographic containment.
Same NPPES enumeration year (2007)
Same-specialty clinicians who entered the NPI registry in the same calendar year, outside this state.
Nearby Sports Medicine (Internal Medicine) Physician Providers in California
Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as Masket.
One of 49 Sports Medicine (Internal Medicine) Physician providers enrolled in California, 11 are shown on this page.
Dr. Melissa Burman
MD
San Diego, CA
Dr. William Cappiello
MD
Santa Clara, CA
Dr. Edward Cheung
MD
Los Angeles, CA
Dr. Philip Cohen
MD
Encino, CA
Dr. Darrell Corben
M.D.
Sunnyvale, CA
Compare Sports Medicine (Internal Medicine) Physician nationally: see state-by-state distribution →
Frequently Asked Questions
What is Harris Masket, M.D.'s specialty? ▼
Harris Masket, M.D. specializes in Sports Medicine (Internal Medicine) Physician and practices in Mill Valley, California. Credentials: M.D..
How much does Harris Masket, M.D. prescribe under Medicare Part D? ▼
In 2024, Harris Masket, M.D. wrote 16 Medicare Part D claims totaling $959 in drug costs for N/A beneficiaries.
Where is Harris Masket, M.D. located? ▼
Harris Masket, M.D. is located at 100 SHORELINE HIGHWAY, Mill Valley, CA, 94941. Phone: (415) 388-5520.
What is Harris Masket, M.D.'s NPI number? ▼
Harris Masket, M.D.'s National Provider Identifier (NPI) is 1801921218, issued on 02/23/2007.
How many Sports Medicine (Internal Medicine) Physician providers are there in the US? ▼
There are 299 Sports Medicine (Internal Medicine) Physician providers across 44 states in the US. The average Sports Medicine (Internal Medicine) Physician provider writes 1,220 Medicare Part D claims per year.
Does Harris Masket, M.D. accept Medicare? ▼
Harris Masket, M.D. appears in CMS Medicare data with 16 Part D claims and N/A Medicare beneficiaries in 2024. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Harris Masket, M.D.'s credentials? ▼
Harris Masket, M.D.'s NPI is 1801921218 with credentials M.D.. 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 (2024). 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 August 2026 (NPPES) / 2024 (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
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 September 2026.