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DR. NATHAN RHYS GWILLIAM MD
NPI 1366882409
Psychiatry & Neurology - Psychiatry in New Haven, CT

Active since July 03, 2013PECOS EnrolledAccepts Medicare Assignment
389 WHITNEY AVE, WHITNEY OFFICE SUITES #2, NEW HAVEN, CT 06511(203) 293-6258 Get Directions Write a Review

NPPES record last updated: April 6, 2026. Verified against the NPPES registry weekly; last sync: August 02, 2026.

Record update history: Apr 6, 2026, Aug 8, 2024, Nov 16, 2021 and 1 more (4 updates tracked since 2021).

About Dr. Nathan Rhys Gwilliam Md NPPES

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

DR. NATHAN RHYS GWILLIAM MD (NPI 1366882409) is an individual psychiatry provider in New Haven, Connecticut, licensed in Connecticut (71782) and active in the NPI registry since July 2013. He is enrolled in Medicare PECOS and is a graduate of Baylor College Of Medicine (2012).

NPPES Registry Identity

NPI1366882409
Entity TypeIndividualMale
Primary Taxonomy2084P0800X
Provider Legal NameDR. NATHAN RHYS GWILLIAMCredential: MD
Location Address389 WHITNEY AVE, WHITNEY OFFICE SUITES #2New Haven, CT 06511
Mailing Address389 Whitney Ave, Whitney Office Suites #2New Haven, CT 06511 · (203) 293-6258
Phone(203) 293-6258
Sole ProprietorYes
Medical School CMSBaylor College Of MedicineGraduated 2012
Enumeration DateJuly 3, 2013
Last NPPES UpdateApril 6, 20264 updates tracked since enumeration
NPPES CertifiedApril 6, 2026
✔ NPI 1366882409 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyPsychiatry & Neurology · PsychiatryAllopathic & Osteopathic Physicians
Taxonomy Code2084P0800X
License✔ Licensed in CT · 71782
Definition
A Psychiatrist specializes in the prevention, diagnosis, and treatment of mental disorders, emotional disorders, psychotic disorders, mood disorders, anxiety disorders, substance-related disorders, sexual and gender identity disorders and adjustment disorders. Biologic, psychological, and social components of illnesses are explored and understood in treatment of the whole person. Tools used may include diagnostic laboratory tests, prescribed medications, evaluation and treatment of psychological and interpersonal problems with individuals and families, and intervention for coping with stress, crises, and other problems.
389 WHITNEY AVE, New Haven, CT 06511
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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

Dr. Nathan Rhys Gwilliam Md 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 ID9638473283
PECOS Enrollment IDI20240522003078
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.

Areas of Expertise CMS Part B claims

Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.

Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more 99215
This service involves a follow-up appointment for existing patients, lasting between 40 to 54 minutes. During this time, your healthcare provider will assess your current health status, discuss any changes or concerns, review your treatment plan, and answer any questions you may have.
21 services14 patients

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 06511 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
$183.10 typical visit price
range $60.82 – $183.10
Typical copayment $45.77 (range $15.20 – $45.77)
Most-billed visit code 99205
Established Patient
$75.55 typical visit price
range $19.76 – $149.26
Typical copayment $18.88 (range $4.94 – $37.31)
Most-billed visit code 99213
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 11

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

MR. KARL B SPEIRS MS MA LMFT
Marriage & Family Therapist
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (860) 508-9465
DR. DAVID L. SNOW PH.D.
Psychologist (Clinical)
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 789-7645
DR. PATRICIA SIMON PHD
Psychologist
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 936-7490
MS. ANNE DUTTON M.S.W.
Social Worker (Clinical)
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 308-0002
DR. JESSE GELLER PHD
Psychologist (Clinical)
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 785-8553
RUTH GELLER LCSW
Social Worker (Clinical)
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 865-1638
DR. NADIA LYNDORA WARD PH.D.
Psychologist
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 789-7645
DR. LES F MARTEL PH.D
Psychologist (Clinical)
389 WHITNEY AVE
NEW HAVEN, CT 06511
South Central Connecticut Planning Region (203) 887-6981

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 Nathan Gwilliam's NPI number?

The NPI number for Nathan Gwilliam is 1366882409. It was assigned to this individual provider in the NPPES registry on July 3, 2013.

Where is Nathan Gwilliam located?

Nathan Gwilliam practices at 389 Whitney Ave Whitney Office Suites #2, New Haven, CT 06511. The listed phone number is (203) 293-6258.

What is Nathan Gwilliam's specialty?

The primary specialty registered for this NPI is Psychiatry & Neurology, specializing in Psychiatry, with taxonomy code 2084P0800X.

Is Nathan Gwilliam enrolled in Medicare?

Yes. Nathan Gwilliam 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.

When was this NPI record last updated?

The NPPES record for Nathan Gwilliam was last updated on April 6, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 4 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.