Tam Nguyen, D.O.
NPI 1841200854 · Internal Medicine Physician · Marysville, CA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Tam Nguyen, D.O. is a Internal Medicine Physician provider in Marysville, CA (NPI 1841200854).
Provider details
- NPI number
- 1841200854
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- D.O.
- Sex
- Male
- Sole proprietor
- Yes
- License
- 20A8322 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
19 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 19 | $93 |
Typical Medicare-allowed amounts for these services range $93–$93 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 130 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 567 | 202 |
| Amlodipine Besylate | 442 | 149 |
| Levothyroxine Sodium | 382 | 119 |
| Lisinopril | 330 | 116 |
| Hydrocodone/Acetaminophenbrand: Hydrocodone-Acetaminophen | 288 | 45 |
| Losartan Potassium | 262 | 93 |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$38 across 2 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-08-09
- Last updated
- 2022-02-11
- Certified
- 2020-03-30
Frequently asked questions
- What is Tam Nguyen's NPI number?
- Tam Nguyen's National Provider Identifier (NPI) is 1841200854, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Tam Nguyen's specialty?
- Tam Nguyen is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Tam Nguyen located?
- Tam Nguyen's practice location on file with NPPES is 414 G St, Marysville, CA 95901-5663.
- What is Tam Nguyen's phone number?
- The practice phone number listed in the NPPES registry for Tam Nguyen is (530) 741-2393.
- Does Tam Nguyen accept Medicare?
- Tam Nguyen is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Tam Nguyen's NPI active?
- Yes — Tam Nguyen's NPI (1841200854) is active in the NPPES registry as of the last update on 2022-02-11.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.