Quick answers
- Where does Mark D. Tieman see patients?
- Medicare's clinician data lists 1 practice location in Commack, NY. Call before your visit to confirm the address.
- What is Mark D. Tieman's specialty?
- Medicare lists Internal Medicine as the primary specialty.
- Does Mark D. Tieman accept Medicare assignment?
- Yes. Medicare's clinician data says Mark D. Tieman accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- Does Mark D. Tieman offer telehealth?
- Medicare's clinician data says Mark D. Tieman offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Mark D. Tieman?
- (631) 858-0400, as listed in official Medicare / NPI Registry data.
- What is Mark D. Tieman's NPI number?
- 1154494003. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where Mark D. Tieman is enrolled with Medicare (CMS data updated 2026-10-02).
- 356 Veterans Memorial HwyCommack, NY 11725 (631) 858‑0400
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Commack
Clinicians with the same Medicare primary specialty in Commack, NY — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Albert Einstein College Of Medicine Of Yeshiva University |
| Graduation year | 1986 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1154494003 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians