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GUILLERMO DIAZ NP-P
NPI 1164975801
Nurse Practitioner - Psychiatric/Mental Health in Hicksville, NY

Active since July 29, 2016PECOS EnrolledAccepts Medicare Assignment
185 W JOHN ST # 113, HICKSVILLE, NY 11801(646) 856-9971(516) 531-8539 Get Directions Write a Review

NPPES record last updated: September 5, 2025. Verified against the NPPES registry weekly; last sync: August 23, 2026.

Record update history: Sep 5, 2025, Aug 6, 2025, Dec 21, 2022 and 1 more (4 updates tracked since 2019).

About Guillermo Diaz Np-p NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

GUILLERMO DIAZ NP-P (NPI 1164975801) is an individual psychiatric/mental health provider in Hicksville, New York, licensed in New York (402068) and active in the NPI registry since July 2016. He is enrolled in Medicare PECOS, maintains a secondary practice location in New Hyde Park, and is a graduate of Other (2016).

NPPES Registry Identity

NPI1164975801
Entity TypeIndividualMale
Primary Taxonomy363LP0808X
Provider Legal NameGUILLERMO DIAZCredential: NP-P
Location Address185 W JOHN ST # 113Hicksville, NY 11801-1007
Mailing Address185 W John St # 113Hicksville, NY 11801-1007 · (646) 856-9971 · Fax (516) 531-8539
Phone(646) 856-9971
Fax(516) 531-8539
Sole ProprietorNo
Medical School CMSOtherGraduated 2016
Enumeration DateJuly 29, 2016
Last NPPES UpdateSeptember 5, 20254 updates tracked since enumeration
NPPES CertifiedSeptember 5, 2025
✔ NPI 1164975801 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyNurse Practitioner · Psychiatric/Mental HealthPhysician Assistants & Advanced Practice Nursing Providers
Taxonomy Code363LP0808X
License✔ Licensed in NY · 402068
185 W JOHN ST # 113, Hicksville, NY 11801
Open in Google Maps ↗

Secondary Practice Location 1

Location 11985 Marcus Ave Ste 110New Hyde Park, NY 11042-2024 · Phone (855) 201-4988

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Oscar Health Maintenance Organization of Florida, Providence Health Plan.Insurance ›

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, and ordering and referring status from the CMS PECOS system.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Guillermo Diaz Np-p 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.

PECOS PAC ID8921383753
PECOS Enrollment IDI20260604002306
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 11801 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$105.06 typical visit price
range $67.40 – $203.53
Typical copayment $26.26 (range $16.85 – $50.88)
Most-billed visit code 99203
Established Patient
$117.62 typical visit price
range $21.66 – $164.45
Typical copayment $29.40 (range $5.41 – $41.11)
Most-billed visit code 99214
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Other Providers at the Same Location NPPES

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

MRS. NORMA A RAMIREZ NP
Nurse Practitioner (Psychiatric/Mental Health)
185 W JOHN ST # 113
HICKSVILLE, NY 11801
Nassau County (646) 240-2375

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 Guillermo Diaz's NPI number?

The NPI number for Guillermo Diaz is 1164975801. It was assigned to this individual provider in the NPPES registry on July 29, 2016.

Where is Guillermo Diaz located?

Guillermo Diaz practices at 185 W John St # 113, Hicksville, NY 11801. The listed phone number is (646) 856-9971.

What is Guillermo Diaz's specialty?

The primary specialty registered for this NPI is Nurse Practitioner, specializing in Psychiatric/Mental Health, with taxonomy code 363LP0808X.

Is Guillermo Diaz enrolled in Medicare?

Yes. Guillermo Diaz 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.

What insurance does Guillermo Diaz accept?

Health plans from Oscar Health Maintenance Organization of Florida and Providence Health Plan list Guillermo Diaz as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.

When was this NPI record last updated?

The NPPES record for Guillermo Diaz was last updated on September 5, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 11 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.