NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1013003201 MD
Verify on CMS → Thomas Williamson, MD
Internal Medicine Physician in Houston, Texas.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 174,792 in 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
10K
Medicare Part D claims · 701 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
90%
generic claims · 10% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$15.61
1 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2024
What the federal data shows
Thomas Williamson, MD filed 9,867 Medicare Part D claims in 2024 as an Internal Medicine Physician in Houston, Texas, prescribing 90% generic.
- 10K
- Part D claims, 2024
- 90%
- generic prescribing
- Likely
- board-certified (heuristic)
- ≥98th
- 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 Thomas Williamson, MD
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 1013003201), first enumerated 10/05/2006.
Source: CMS NPPES
- Reported
Medicare Part D participation
Filed 9,867 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
Heuristic suggests board-certified status based on ABMS-eligible specialty taxonomy plus active CMS participation signals — not a direct ABMS verification.
- Reported
Hospital affiliations
1 CMS Care Compare hospital affiliation on record — practice footprint from the Doctors and Clinicians file.
Source: CMS Care Compare
- Reported
Industry payment transparency
$15.61 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
Texas statewide board action statistics are published annually — these figures describe aggregate state activity, not Thomas Williamson, MD's individual license status. Verify directly with the state medical board.
Source: TMB annual report 2023
- 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.
CMS NPPES provider registry desk
NPI 1013003201 · Internal Medicine Physician
NPI-10 · ENUM-LEGACY · TAX-MEGA · RX-MID · BOOK-MID · PHOTO-ENUM
- NPI-10 1013003201
- ENUM-LEGACY 2006
- TAX-MEGA 175K Internal Medicine
- RX-MID 9,867
- BOOK-MID 11,069 in Texas
- PHOTO-ENUM Kurt Duffens · 2006
Thomas Williamson, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2024, across all CMS prescribers nationally
9,867 ≥ 98th percentile 98% 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 certification likely (heuristic, not verified)
Thomas Williamson, MD practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation - signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Thomas Williamson, MD?
Quality data not reportedPrimary specialty
Internal Medicine Physician
Medicare Part D claims
9,867 254% vs specialty avg
Specialty distribution in Texas
How Internal Medicine Physician compares to other specialties among Texas 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 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 | 1013003201 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | MD |
| Gender | Male |
| NPI Issued | 10/05/2006 |
Hospital and facility affiliations
Facilities where Thomas Williamson, MD bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" - a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.
Kelsey-Seybold Medical Group, PLLC
Houston, TX
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
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 Thomas Williamson, MD. Source: openpaymentsdata.cms.gov.
Total received
$16
Largest payer
AstraZeneca Pharmaceuticals LP
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 - Texas TMB 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 ~77K Texas medical licensees in 2023 - they are NOT specific to Thomas Williamson, MD. To verify Thomas Williamson, MD's current license status, search the TMB public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.
344
Total board actions, Texas 2023
Across 334 cases
4.47
Actions per 1,000 licensees
Texas statewide rate
probation
Most common action type
94 cases
TMB 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 Texas disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.
Brand vs generic prescribing mix · Typical
Thomas Williamson, MD - brand share 10.0%
Internal Medicine Physician average
10% brand-name claims vs 90% generic, on 9,867 2024 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 2024.
9,867
Total Claims
$845K
Total Drug Cost
701
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 21,777.9
- Total Day Supply
- 639,539
- Brand vs Generic
- 10% brand / 90% generic
- Brand Drug Cost
- $596K
- Generic Drug Cost
- $247K
- Opioid Claims
- 124 (1.3% rate)
- Antibiotic Claims
- 111
Patient Demographics
- Average Patient Age
- 76.0 years
- Avg HCC Risk Score
- 1.68
- Gender Split
- 40% female / 60% male
- Age Distribution
- <65: 26, 65-74: 265, 75-84: 310, 85+: 100
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2024. Based on Medicare Part D data only.
What Thomas Williamson, MD prescribes most
Top Medicare Part D drugs by claim count, 2024
- Atorvastatin Calcium
Atorvastatin Calcium
630 claims
- Amlodipine Besylate
Amlodipine Besylate
420 claims
- Levothyroxine Sodium
Levothyroxine Sodium
301 claims
- Lisinopril
Lisinopril
295 claims
- Omeprazole
Omeprazole
283 claims
- Tamsulosin Hcl
Tamsulosin Hcl
270 claims
- Losartan Potassium 251
Losartan Potassium
251 claims
- Metformin Hcl 229
Metformin Hcl
229 claims
| Drug | Claims |
|---|---|
| Atorvastatin Calcium | 630 |
| Amlodipine Besylate | 420 |
| Levothyroxine Sodium | 301 |
| Lisinopril | 295 |
| Omeprazole | 283 |
| Tamsulosin Hcl | 270 |
| Losartan Potassium | 251 |
| Metformin Hcl | 229 |
| Rosuvastatin Calcium | 216 |
| Simvastatin | 214 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Internal Medicine Physician Overview
How Thomas Williamson, MD fits within the Internal Medicine Physician landscape nationally.
174,792
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,785
Avg Claims per Provider
Thomas Williamson, MD's 9,867 claims are above the specialty average of 2,785.
Nationwide Internal Medicine Physician peers with similar MIPS or enrollment year
Two federal-record peer sets for Williamson, both outside Texas so the neighborhoods are not geographic containment.
Same NPPES enumeration year (2006)
Same-specialty clinicians who entered the NPI registry in the same calendar year, outside this state.
Nearby Internal Medicine Physician Providers in Texas
Other clinicians with the same primary specialty enrolled in Texas, drawn from the same CMS NPPES roster as Williamson.
One of 11,069 Internal Medicine Physician providers enrolled in Texas, 5 are shown here.
Dr. Muhammad A. Sattar
MD
Dallas, TX
Dr. Gayatri Aaluri
MD
Galveston, TX
Anunaya Aashish
Denton, TX
Dr. Queenie Ann Abad
M.D.
San Antonio, TX
Dr. Fuad Abaleka
M.D
Lubbock, TX
Compare Internal Medicine Physician nationally: see state-by-state distribution →
Frequently Asked Questions
What is Thomas Williamson, MD's specialty? ▼
Thomas Williamson, MD specializes in Internal Medicine Physician and practices in Houston, Texas. Credentials: MD.
How much does Thomas Williamson, MD prescribe under Medicare Part D? ▼
In 2024, Thomas Williamson, MD wrote 9,867 Medicare Part D claims totaling $845K in drug costs for 701 beneficiaries.
Where is Thomas Williamson, MD located? ▼
Thomas Williamson, MD is located at 560 MEYERLAND PLAZA MALL, Houston, TX, 77096. Phone: (713) 442-3222.
What is Thomas Williamson, MD's NPI number? ▼
Thomas Williamson, MD's National Provider Identifier (NPI) is 1013003201, issued on 10/05/2006.
Does Thomas Williamson, MD prescribe more brand-name or generic drugs? ▼
Thomas Williamson, MD's prescribing is 10% brand-name and 90% generic drugs by claim count, with $596K in brand drug costs.
Does Thomas Williamson, MD prescribe opioids? ▼
Yes, Thomas Williamson, MD had 124 opioid claims in 2024 with an opioid prescribing rate of 1.3%.
How many Internal Medicine Physician providers are there in the US? ▼
There are 174,792 Internal Medicine Physician providers across 56 states in the US. The average Internal Medicine Physician provider writes 2,785 Medicare Part D claims per year.
What drugs does Thomas Williamson, MD prescribe most often? ▼
Based on 2024 Medicare Part D data, Thomas Williamson, MD's most frequently prescribed drugs include Atorvastatin Calcium, Amlodipine Besylate, Levothyroxine Sodium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Thomas Williamson, MD accept Medicare? ▼
Thomas Williamson, MD appears in CMS Medicare data with 9,867 Part D claims and 701 Medicare beneficiaries in 2024. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Thomas Williamson, MD's credentials? ▼
Thomas Williamson, MD's NPI is 1013003201 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 (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 August 2026.