ZACHARY JACOB GREENSTEIN DO
NPI 1174151872
Internal Medicine - Critical Care Medicine in New York, NY
About Zachary Jacob Greenstein Do NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
ZACHARY JACOB GREENSTEIN DO (NPI 1174151872) is an individual critical care medicine provider in New York, New York, licensed in New York (323643) and active in the NPI registry since March 2020. He is enrolled in Medicare PECOS, is affiliated with Vassar Brothers Medical Center, and is a graduate of Other (2020).
NPPES Registry Identity
Specialties & Licenses 2
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Zachary Jacob Greenstein Do is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
2Medicare enrollment records show Zachary Greenstein reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
New Hyde Park, NY 11040
- Reassigned Medicare billing, New York enrollment
- 9,353 clinicians in this Medicare group
Poughkeepsie, NY 12601
- Reassigned Medicare billing, New York enrollment
- 638 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Hospital Affiliations CMS Care Compare 3
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Vassar Brothers Medical Center
Acute Care Hospitals · Poughkeepsie, NYNorthern Dutchess Hospital
Acute Care Hospitals · Rhinebeck, NYLenox Hill Hospital
Acute Care Hospitals · New York, NYPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 10075 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
NEW YORK, NY 10075
NEW YORK, NY 10075
NEW YORK, NY 10075
NEW YORK, NY 10075
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 Zachary Greenstein's NPI number?
The NPI number for Zachary Greenstein is 1174151872. It was assigned to this individual provider in the NPPES registry on March 29, 2020.
Where is Zachary Greenstein located?
Zachary Greenstein practices at 100 E 77th St, New York, NY 10075. The listed phone number is (212) 434-2000.
What is Zachary Greenstein's specialty?
The primary specialty registered for this NPI is Internal Medicine, specializing in Critical Care Medicine, with taxonomy code 207RC0200X.
Is Zachary Greenstein enrolled in Medicare?
Yes. Zachary Greenstein is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Zachary Greenstein's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Zachary Greenstein reassigns Medicare benefits to 2 organizations: North Shore - Lij Medical PC (New Hyde Park, NY) and Nuvance Health Medical Practice PC (Poughkeepsie, NY). Each 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 Zachary Greenstein's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
Is Zachary Greenstein affiliated with any hospitals?
According to CMS data, Zachary Greenstein is affiliated with Vassar Brothers Medical Center, Northern Dutchess Hospital and Lenox Hill Hospital.
When was this NPI record last updated?
The NPPES record for Zachary Greenstein was last updated on April 28, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 5 months 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.
# Zachary Jacob Greenstein, DO · NPI 1174151872
Critical Care Medicine physician in New York, New York. Individual provider, active in the CMS NPPES registry since March 29, 2020.
## Identity
- **NPI:** 1174151872 (Entity type: Individual)
- **Enumerated:** March 29, 2020
- **Primary specialty:** Internal Medicine - Critical Care Medicine · taxonomy 207RC0200X
- **State license:** 323643 (New York)
- **Sole proprietor:** No
## Practice location
- **Address:** 100 E 77TH ST, New York, NY 10075-1850
- **Phone:** (212) 434-2000
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 2 organizations under Medicare reassignment (form CMS-855R): North Shore - Lij Medical PC (NPI 1790043479, New Hyde Park, NY); Nuvance Health Medical Practice PC (NPI 1437358033, Poughkeepsie, NY) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Other, class of 2020
## Record status
- **NPPES last updated:** April 28, 2026
---
Source: [NPI Profile](https://npiprofile.com/npi/1174151872) · Data from the CMS NPPES public registry.