MARK T. FAHLEN, MD, INC. A PROFESSIONAL MEDICAL CORPORATION
NPI 1659537264
Internal Medicine - Nephrology in Modesto, CA
About Mark T. Fahlen, Md, Inc. A Professional Medical Corporation NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
MARK T. FAHLEN, MD, INC. A PROFESSIONAL MEDICAL CORPORATION (NPI 1659537264) is a healthcare organization registered as a nephrology in Modesto, California and active in the NPI registry since August 2008. The organization lists Mark Theodore Fahlen, President, as its authorized official.
NPPES Registry Identity
Specialties & Licenses
Other Identifiers 1
Group Practice 1
Medicare Participation & PECOS CMS
Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.
Medicare Enrollment Status
Enrolled in Medicare (PECOS)
Mark T. Fahlen, Md, Inc. A Professional Medical Corporation is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Clinicians Billing Medicare Through This Organization
Medicare enrollment records show 1 clinician reassigns Medicare billing to Mark T. Fahlen, MD, Inc. A Professional Medical Corporation, which bills Medicare for the services this clinician delivers.
Clinician (1)
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Mark T. Fahlen, MD, Inc. A Professional Medical Corporation's NPI number?
The NPI number for Mark T. Fahlen, MD, Inc. A Professional Medical Corporation is 1659537264. It was assigned to this organization in the NPPES registry on August 3, 2008.
Where is Mark T. Fahlen, MD, Inc. A Professional Medical Corporation located?
Mark T. Fahlen, MD, Inc. A Professional Medical Corporation is located at 1400 Florida Ave Suite 109, Modesto, CA 95350. The listed phone number is (209) 544-2910.
What is Mark T. Fahlen, MD, Inc. A Professional Medical Corporation's specialty?
The primary specialty registered for this NPI is Internal Medicine, specializing in Nephrology, with taxonomy code 207RN0300X.
Is Mark T. Fahlen, MD, Inc. A Professional Medical Corporation enrolled in Medicare?
Yes. Mark T. Fahlen, MD, Inc. A Professional Medical Corporation is registered in the Medicare PECOS enrollment system.
How many clinicians bill Medicare through Mark T. Fahlen, MD, Inc. A Professional Medical Corporation?
According to the CMS Revalidation Reassignment List (October 2026 release), 1 clinician (Nephrology) reassigns their Medicare billing to Mark T. Fahlen, MD, Inc. A Professional Medical Corporation. A reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for the clinician's services. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
When was this NPI record last updated?
The NPPES record for Mark T. Fahlen, MD, Inc. A Professional Medical Corporation was last updated on August 2, 2011. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 15 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Mark T. Fahlen, Md, Inc. A Professional Medical Corporation · NPI 1659537264
Nephrology organization in Modesto, California. Organization record, active in the CMS NPPES registry since August 3, 2008.
## Identity
- **NPI:** 1659537264 (Entity type: Organization)
- **Enumerated:** August 3, 2008
- **Primary specialty:** Internal Medicine - Nephrology · taxonomy 207RN0300X
- **Organization subpart:** No
- **Authorized official:** Mark Fahlen, PRESIDENT
## Practice location
- **Address:** 1400 FLORIDA AVE, SUITE 109, Modesto, CA 95350-4422
- **Phone:** (209) 544-2910 · **Fax:** (209) 544-2253
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Clinicians billing through this organization:** 1 clinician (Nephrology) reassigns Medicare billing to this organization (form CMS-855R) · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** August 2, 2011
- **Other identifiers:** Medicare UPIN H85858 (CA)
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Source: [NPI Profile](https://npiprofile.com/npi/1659537264) · Data from the CMS NPPES public registry.