MARK TIEMAN, MD, PC
NPI 1821375940
Clinic/Center - Primary Care in Commack, NY
About Mark Tieman, Md, Pc NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
MARK TIEMAN, MD, PC (NPI 1821375940) is a healthcare organization registered as a primary care in Commack, New York and active in the NPI registry since November 2011. The organization lists Mark Daryl Tieman, President, as its authorized official.
NPPES Registry Identity
Specialties & Licenses
Medicare Participation & PECOS CMS
Medicare enrollment, revalidation and the clinicians who bill Medicare through this organization, from CMS.
Medicare Enrollment Status
Enrolled in Medicare (PECOS)
Mark Tieman, Md, Pc is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Medicare Revalidation Due Date
Revalidation due by January 31, 2027
Medicare-enrolled providers and suppliers confirm their enrollment information with CMS on a set cycle, every 5 years for most and every 3 years for medical equipment suppliers. CMS sets the due date for each enrollment.
Clinicians Billing Medicare Through This Organization
2Medicare enrollment records show 2 clinicians reassign Medicare billing to Mark Tieman, MD, PC, which bills Medicare for the services they deliver. Of these, 2 practice at this address. They are listed nearest first.
Clinicians, nearest first (2)
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 Tieman, MD, PC's NPI number?
The NPI number for Mark Tieman, MD, PC is 1821375940. It was assigned to this organization in the NPPES registry on November 3, 2011.
Where is Mark Tieman, MD, PC located?
Mark Tieman, MD, PC is located at 356 Veterans Memorial Hwy, Commack, NY 11725. The listed phone number is (631) 858-0400.
What is Mark Tieman, MD, PC's specialty?
The primary specialty registered for this NPI is Clinic/Center, specializing in Primary Care, with taxonomy code 261QP2300X.
Is Mark Tieman, MD, PC enrolled in Medicare?
Yes. Mark Tieman, MD, PC is registered in the Medicare PECOS enrollment system.
When is Mark Tieman, MD, PC's Medicare revalidation due?
According to the CMS Revalidation Due Date List (October 2026 release), the Medicare Non-DME Part B enrollment for this organization (New York, Clinic/Group Practice) is due for revalidation by January 31, 2027. Medicare providers and suppliers revalidate their enrollment every 5 years, and medical equipment suppliers every 3 years. Confirm current requirements with your Medicare Administrative Contractor.
How many clinicians bill Medicare through Mark Tieman, MD, PC?
According to the CMS Revalidation Reassignment List (October 2026 release), 2 clinicians reassign their Medicare billing to Mark Tieman, MD, PC, in Internal Medicine and Nurse Practitioner. 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. Of these, 2 practice at this address. 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 Tieman, MD, PC was last updated on November 3, 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 Tieman, Md, Pc · NPI 1821375940
Primary Care organization in Commack, New York. Organization record, active in the CMS NPPES registry since November 3, 2011.
## Identity
- **NPI:** 1821375940 (Entity type: Organization)
- **Enumerated:** November 3, 2011
- **Primary specialty:** Clinic/Center - Primary Care · taxonomy 261QP2300X
- **Organization subpart:** No
- **Authorized official:** Mark Tieman, PRESIDENT
## Practice location
- **Address:** 356 VETERANS MEMORIAL HWY, Commack, NY 11725-4343
- **Phone:** (631) 858-0400 · **Fax:** (631) 543-2785
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Medicare revalidation due:** January 31, 2027 (Non-DME Part B, New York, Clinic/Group Practice) · CMS Revalidation Due Date List, October 2026 release
- **Clinicians billing through this organization:** 2 clinicians in 2 Medicare specialties reassign Medicare billing to this organization (form CMS-855R); largest: Internal Medicine (1), Nurse Practitioner (1); 2 practice at this address · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** November 3, 2011
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Source: [NPI Profile](https://npiprofile.com/npi/1821375940) · Data from the CMS NPPES public registry.