Timothy Ian Mackenzie Mercer, MD
Internal Medicine Physician · Austin, TX
Timothy Ian Mackenzie Mercer, MD is an internal medicine physician with a practice address in Austin, Texas, and NPI 1215337092, issued on Aug 28, 2014. Check the license (Texas R4099, as entered in NPPES) on the Texas Medical Board; the Medicare figures below come from public CMS files.
- Name
- Timothy Ian Mackenzie Mercer
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- R4099 TX
Self-reported in NPPES; status is on the state search - Practice location
- 1601 Trinity St, Austin, TX 78712
- Phone
- (512) 978-8130
- Enumerated
- Aug 28, 2014
- Record last updated
- Jul 26, 2025
- Medicare enrollment
- Enrolled (PECOS I20210510000665); accepts Medicare assignment
- Medical or professional school
- Indiana University School Of Medicine, 2011
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 9,175 in Texas → Look up another NPI →
Also registered at 1601 Trinity St
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Timothy Ian Mackenzie Mercer in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersTexas Medical Board
Search for license R4099Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
83% fewer Medicare Part D claims than the average internal medicine physician in 2024
549 Medicare Part D claims for 48 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 14 claims were for opioids.
Most prescribed
- Atorvastatin Calcium53 claims
- Amlodipine Besylate42 claims
- Albuterol Sulfate Hfa35 claims
- Losartan Potassium23 claims
- Sertraline Hcl22 claims
- Lisinopril21 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.
The practice group's MIPS final score for 2023 (Medicare payment program): 72.5 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023, group reporting; category weights for 2023 (qpp.cms.gov).
Bills Medicare through one group practice
- Seton Family OF DoctorsAustin, TX
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Timothy Ian Mackenzie Mercer among 9,175 internal medicine physician records in Texas
Timothy Ian Mackenzie Mercer, MD is one of 9,175 internal medicine physician records with a practice address in Texas. 82% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2014, is newer than 69% of them.
- NPI issued2014 · 69% of these records are older, 29% newer
- In a Medicare fileYes · 82% of these records are
- In the CMS Doctors and Clinicians fileYes · 66% of these records are
- Graduated2011 · median 2004 among the 6,088 with a school on file
- Record last updated2025 · 49% 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 Texas practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
606 internal medicine physician records list a practice address in Austin
They are 606 of the 26,585 NPPES records with a practice address in Austin, and 9,175 internal medicine physician records in Texas.
All 9,175 in Texas → Every provider in Austin → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Peter Alperin, M.D.Austin, TX 787121578532370
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- William Brode, MDAustin, TX 787121619362217
- Neesha Kurian, M.D.Austin, TX 787121477591824
- Jeffrey Latimer, M.D.Austin, TX 787121194950600
- Mahsa Mansouri, MDAustin, TX 787121982199386
- Melinda McMichael, M.D.Austin, TX 787121174596878
- Paul Mueller, M.D.Austin, TX 787121427021955
Common questions
What is Timothy Ian Mackenzie Mercer, MD's NPI number?
Timothy Ian Mackenzie Mercer, MD's National Provider Identifier (NPI) is 1215337092, issued on Aug 28, 2014. An NPI identifies a provider in billing; it is not a license.
Where is Timothy Ian Mackenzie Mercer, MD located?
The NPPES record lists a practice address at 1601 Trinity St, Austin, TX, 78712. Phone: (512) 978-8130. Providers update this record themselves, so call before visiting.
How can I verify Timothy Ian Mackenzie Mercer, MD's license?
NPPES lists Texas license number R4099, as entered by the provider. Search the Texas Medical Board at https://profile.tmb.state.tx.us/Search.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Timothy Ian Mackenzie Mercer, MD prescribe under Medicare Part D?
In 2024, Timothy Ian Mackenzie Mercer, MD had 549 Medicare Part D claims for 48 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
What is Timothy Ian Mackenzie Mercer, MD's MIPS final score?
The 2023 MIPS final score is 72.5 of 100, reported for the practice group. The average among 454,083 clinicians with a measured score was 83.5.
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.