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SEAN THOMAS WILLIAMS M.D.
NPI 1255712626
Emergency Medicine in Chicago, IL

Active since June 11, 2015PECOS Enrolled
5645 W ADDISON ST, DEPT OF EMERGENCY MEDICINE, CHICAGO, IL 60634(773) 794-8383(773) 794-4686 Get Directions Write a Review

NPPES record last updated: March 18, 2021. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Mar 18, 2021, Oct 10, 2018, Apr 17, 2018 (3 updates tracked since 2018).

About Sean Thomas Williams M.d. NPPES

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

SEAN THOMAS WILLIAMS M.D. (NPI 1255712626) is an individual emergency medicine provider in Chicago, Illinois, licensed in Illinois (036144052) and active in the NPI registry since June 2015. He is enrolled in Medicare PECOS and maintains a secondary practice location in Chicago.

NPPES Registry Identity

NPI1255712626
Entity TypeIndividualMale
Primary Taxonomy207P00000X
Provider Legal NameSEAN THOMAS WILLIAMSCredential: M.D.
Location Address5645 W ADDISON ST, DEPT OF EMERGENCY MEDICINEChicago, IL 60634-4403
Mailing Address5645 W Addison St, Dept Of Emergency MedicineChicago, IL 60634-4403
Phone(773) 794-8383
Fax(773) 794-4686
Sole ProprietorNo
Enumeration DateJune 11, 2015
Last NPPES UpdateMarch 18, 20213 updates tracked since enumeration
NPPES CertifiedMarch 18, 2021
✔ NPI 1255712626 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyEmergency MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207P00000X
License✔ Licensed in IL · 036144052
Definition
An emergency physician focuses on the immediate decision making and action necessary to prevent death or any further disability both in the pre-hospital setting by directing emergency medical technicians and in the emergency department. The emergency physician provides immediate recognition, evaluation, care, stabilization and disposition of a generally diversified population of adult and pediatric patients in response to acute illness and injury.
5645 W ADDISON ST, Chicago, IL 60634
Open in Google Maps ↗

Secondary Practice Location 1

Location 17435 W Talcott AveChicago, IL 60631-3707 · Phone (773) 774-8000

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Sean Thomas Williams M.d. is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

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.

Medicare Billing Reassignments

2

Medicare enrollment records show Sean Williams reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Community First Healthcare Of Illinois, Inc.
Same address
Diagnostic Radiology
5645 W ADDISON ST
Chicago, IL 60634
  • Reassigned Medicare billing, Illinois enrollment
  • 174 clinicians in this Medicare group
NPI 1053102269 (773) 282-7000
Cepamerica Illinois LLP
3.8 mi
Emergency Medicine
7435 W TALCOTT AVE
Chicago, IL 60631
  • Reassigned Medicare billing, Illinois enrollment
  • 982 clinicians in this Medicare group
NPI 1518415751 (773) 774-8000

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Areas of Expertise CMS Part B claims 2

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.

Emergency department visit with high level of medical decision making 99285
An emergency department visit for severe conditions is when you urgently seek medical help due to serious health issues. These could be severe injuries, breathing problems, unbearable pain, or sudden severe illness. Doctors and nurses will provide immediate care to stabilize your condition.
19 services19 patients
Electrocardiogram (ecg) 1 to 3 leads with review by physician only 93042
An Electrocardiogram (ECG) is a non-invasive test that records the electrical activity of your heart. 1 to 3 leads or sensors are placed on your body to capture this data. A physician then reviews the results to evaluate your heart's health.
14 services14 patients

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60634 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
$94.06 typical visit price
range $60.08 – $183.39
Typical copayment $23.51 (range $15.02 – $45.84)
Most-billed visit code 99203
Established Patient
$105.70 typical visit price
range $18.97 – $148.12
Typical copayment $26.42 (range $4.74 – $37.03)
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 20

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

DR. AARON DANIEL KALLSNICK M.D.
Anesthesiology
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 282-7000
DR. DEVON BEER PT, DPT
Physical Therapist
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 794-7690
DR. EMILY KASSAB DPT
Physical Therapist
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 794-7690
NICHOLAS MORRELL DPT
Physical Therapist
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 282-7000
COMMUNITY FIRST HEALTHCARE OF ILLINOIS, INC
General Acute Care Hospital
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 282-7000
COMMUNITY FIRST HEALTHCARE OF ILLINOIS, INC.
Radiology (Diagnostic Radiology)
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 282-7000
ADEKUNLE ADESUYI CRNA
Nurse Anesthetist, Certified Registered
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 282-7000
KRISTIN ROSS P.T.
Physical Therapist
5645 W ADDISON ST
CHICAGO, IL 60634
Cook County (773) 794-7690

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 Sean Williams's NPI number?

The NPI number for Sean Williams is 1255712626. It was assigned to this individual provider in the NPPES registry on June 11, 2015.

Where is Sean Williams located?

Sean Williams practices at 5645 W Addison St Dept Of Emergency Medicine, Chicago, IL 60634. The listed phone number is (773) 794-8383.

What is Sean Williams's specialty?

The primary specialty registered for this NPI is Emergency Medicine with taxonomy code 207P00000X.

Is Sean Williams enrolled in Medicare?

Yes. Sean Williams is registered in the Medicare PECOS enrollment system.

Which organizations bill Medicare for Sean Williams's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Sean Williams reassigns Medicare benefits to 2 organizations: Community First Healthcare Of Illinois, Inc. (Chicago, IL) and Cepamerica Illinois LLP (Chicago, IL). 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 Sean Williams's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

When was this NPI record last updated?

The NPPES record for Sean Williams was last updated on March 18, 2021. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 5 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.