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Internal Medicine Providers in San Marcos, CA

Browse 17 Internal Medicine providers listed in NPPES with a practice address in San Marcos, California.

17 Healthcare Providers

How San Marcos compares with the U.S.

San Marcos has 18 clinicians in Internal Medicine per 100,000 residents, about 40% of the U.S. rate of 44.

That is 17 active clinicians in Internal Medicine with a practice address in San Marcos, for a population of 94,882.

The California rate is 45 per 100,000 residents.

What these numbers mean

Clinicians per 100,000 residents compares places of different sizes. We count active clinicians who list a practice address in the area in the federal NPI registry (NPPES) and divide by the number of people who live there, according to the U.S. Census Bureau. The U.S. rate is the same calculation for the whole country.

A higher number does not mean it is easier to get an appointment, that wait times are shorter, or that care is better. It also does not show how many clinicians are accepting new patients or which insurance plans they take. A lower number does not by itself mean there is a shortage.

City counts use the city name in each clinician's practice address. That postal city can cover a larger or smaller area than the city limits the Census Bureau uses for population, and many clinicians list only one address even if they work in several places.

100% of clinicians in Internal Medicine in San Marcos listed in the CMS Medicare file (16 of 16) accept Medicare assignment. That is similar to the California share of 96%.

What is Medicare assignment?

A clinician who accepts Medicare assignment agrees to take the Medicare-approved amount as full payment for services that Original Medicare covers. You usually still pay your deductible and coinsurance. This comes from the CMS Doctors and Clinicians file and applies to Original Medicare only. Medicare Advantage plans have their own provider networks. It does not show whether a clinician is taking new patients.

Some clinicians are listed as "may accept assignment," which means they can decide case by case. Clinicians without an assignment flag, or who are not in the CMS file, are not counted as accepting assignment. That does not mean they refuse Medicare. Ask the office before your visit.

19% of clinicians in Internal Medicine in San Marcos listed in the CMS Medicare file (3 of 16) have a CMS telehealth indicator, meaning their recent Medicare claims include telehealth services. That is lower than the California share of 38%.

About the telehealth indicator

The telehealth indicator comes from CMS. It marks clinicians whose recent paid Medicare claims include services delivered by telehealth. It means a clinician has provided some services by telehealth, not that every visit can be done online. A clinician without the indicator may still offer telehealth, for example to patients who are not on Medicare. Ask the office which visits can be done by video or phone.

These figures summarize public federal data. They do not measure quality of care, appointment availability, or whether a clinician accepts your insurance or new patients. Registry addresses can be out of date. Please confirm details directly with the office and your plan. This information is not medical advice.

Prepared by T-MedInfo from NPPES, CMS and U.S. Census Bureau data. Questions or corrections: support@true-medinfo.com ยท Methodology

Sources: Clinician counts and practice addresses: NPPES NPI Registry, Centers for Medicare & Medicaid Services (CMS), data as of August 2026. Medicare assignment and telehealth indicators: CMS Doctors and Clinicians National Downloadable File. Population: U.S. Census Bureau, American Community Survey 2020-2024 5-Year Estimates, Table B01003 (Total Population).

Internal Medicine Medicare (PECOS) Enrollment & Ordering Eligibility

Medicare enrollment and order/referring eligibility listed by CMS for Internal Medicine practitioners in San Marcos, CA

Source: CMS PECOS
PECOS Enrolled Specialists 16 In San Marcos, CA
Part B Lab & Imaging Eligible 16 Diagnostic Referrals
DME Ordering Eligible 16 Durable Medical Equipment
Home Health Agency Referrals 16 HHA Ordering Eligible
Showing 1โ€“17 of 17 providers
With recent CMS data first, then Aโ€“Z

Dr. Mona Arasoghli , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
400 Craven Rd, San Marcos, CA 920784201
Phone: 8002905000
NPI Identifier 1790193738
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Dr. Meenu Bawa , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
400 Craven Rd, San Marcos, CA 920784201
Phone: 6193238789
NPI Identifier 1154598571
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Dr. Shreya Chandra , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
150 Valpreda Rd, San Marcos, CA 920692973
Phone: 7607366700
NPI Identifier 1972519825
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Dr. Justin Alexander Charles , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment Telehealth Services Available
314 S Twin Oaks Valley Rd Ste 114, San Marcos, CA 920784390
Phone: 4423722330
NPI Identifier 1811552771
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Active NPI Status Accepts Medicare Assignment
400 Craven Rd, San Marcos, CA 920784201
Phone: 8772360333
NPI Identifier 1669738928
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Dr. Joseph Czvik , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
1635 Lake San Marcos Dr, Ste 202, San Marcos, CA 920784661
Phone: 7604711020
NPI Identifier 1528084340
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Dr. Sze Hoay Ding , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
400 Craven Rd, San Marcos, CA 920784201
Phone: 6193187476
NPI Identifier 1023239035
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Dr. Kathryn Davis Germeraad , DO

Internal Medicine

Active NPI Status Accepts Medicare Assignment
314 S Twin Oaks Valley Rd Ste 114, San Marcos, CA 920784390
Phone: 8585541212
NPI Identifier 1649830498
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Dr. Lauren Jefferis , MD

Internal Medicine

Active NPI Status
150 Valpreda Rd, San Marcos, CA 920692973
Phone: 7607366700
NPI Identifier 1346354776
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Dr. Francisco Marquez , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment Telehealth Services Available
400 Craven Rd, San Marcos, CA 920784201
Phone: 7605104313
NPI Identifier 1316190747
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Dr. Minh Quoc Nguyen , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
885 Orion Way, San Marcos, CA 920780914
Phone: 6197570141
NPI Identifier 1154403640
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Dr. Samuel Poniachik , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
150 Valpreda Rd, San Marcos, CA 920692973
Phone: 7607366700
NPI Identifier 1467485078
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Dr. Marie Ann Russell , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
150 Valpreda Rd, San Marcos, CA 920692973
Phone: 7607368689
NPI Identifier 1609947449
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Dr. Tyler Sprague , DO

Internal Medicine

Active NPI Status Accepts Medicare Assignment
1582 W San Marcos Blvd Ste 100, San Marcos, CA 920784081
Phone: 7603041383
NPI Identifier 1881077428
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Dr. Arturo Magno Tolentino , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
2085 Montiel Rd Ste 102, San Marcos, CA 920693563
Phone: 8338674642
NPI Identifier 1609066018
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Dr. Tina Tran , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment Telehealth Services Available
111 Campus Way Ste 301, San Marcos, CA 920784212
Phone: 7608065700
NPI Identifier 1285263830
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Dr. Izabela Witczak , MD

Internal Medicine

Active NPI Status Accepts Medicare Assignment
150 Valpreda Rd, San Marcos, CA 920692973
Phone: 7607366700
NPI Identifier 1184735201
View Full Profile

Frequently Asked Questions about Internal Medicine in San Marcos

How do I check a Internal Medicine practitioner's license?

Each practitioner profile shows the NUCC taxonomy code and any state license number the practitioner reported to NPPES, plus a link to the California licensing board lookup. NPPES entries are self-reported; current license status is published only by the state board.

Why is a practitioner missing from this list?

This list shows NPI records that are active in NPPES. A deactivated NPI keeps its profile with the deactivation date and practice history; find it with the site search by name or NPI number.