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JAMES AHN
NPI 1457594574
Internal Medicine in Chicago, IL

Active since April 20, 2009PECOS Enrolled
97.71/100
CMS Quality Rating
5841 S MARYLAND AVE, CHICAGO, IL 60637(888) 824-0200 Get Directions Write a Review

NPPES record last updated: October 24, 2022. Verified against the NPPES registry weekly; last sync: November 08, 2026.

Record update history: Oct 24, 2022, May 19, 2022, Apr 18, 2022 (3 updates tracked since 2022).

About James Ahn NPPES

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

JAMES AHN (NPI 1457594574) is an individual internal medicine provider in Chicago, Illinois, licensed in Illinois (036125480) and active in the NPI registry since April 2009. He is enrolled in Medicare PECOS.

NPPES Registry Identity

NPI1457594574
Entity TypeIndividualMale
Primary Taxonomy207R00000X
Provider Legal NameJAMES AHN
Location Address5841 S MARYLAND AVEChicago, IL 60637-1443
Mailing Address150 Harvester Dr, Suite 300Burr Ridge, IL 60527-5919
Phone(888) 824-0200
Sole ProprietorNo
Enumeration DateApril 20, 2009
Last NPPES UpdateOctober 24, 20223 updates tracked since enumeration
✔ NPI 1457594574 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207R00000X
License✔ Licensed in IL · 036125480
Definition
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.
5841 S MARYLAND AVE, Chicago, IL 60637
Open in Google Maps ↗

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Oscar Health.Insurance ›

Medicare Participation & PECOS CMS

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

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

James Ahn 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 James Ahn reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

The University Of Chicago Medical Center
Same address
General Acute Care Hospital
5841 S MARYLAND AVE
Chicago, IL 60637
  • Reassigned Medicare billing, Illinois enrollment
  • 1,905 clinicians in this Medicare group
NPI 1033218128 (773) 702-1530
University Of Chicago
Same address
Multi-Specialty
5841 S MARYLAND AVE, UCPG/MC 1099
Chicago, IL 60637
  • Reassigned Medicare billing, Illinois enrollment
  • 2,237 clinicians in this Medicare group
NPI 1821048786 (773) 702-9200

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.
92 services89 patients
Emergency department visit with moderate level of medical decision making 99284
An emergency department visit for a high-severity issue means you're experiencing a serious health problem that needs immediate attention. This could be a severe injury, serious illness, or life-threatening condition. Medical professionals will provide urgent care to stabilize your condition.
15 services15 patients

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60637 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
$138.86 typical visit price
range $60.08 – $183.39
Typical copayment $34.71 (range $15.02 – $45.84)
Most-billed visit code 99204
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.

Medicare Quality Performance CMS QPP · MIPS

Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.

97.71/100
MIPS Final ScoreMerit-based Incentive Payment System · CMS Quality Payment Program
Scored through an Alternative Payment Model
Quality75.43
Promoting Interoperability100
Improvement Activities40

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. DON MARTINEZ M.D.
Radiology (Diagnostic Radiology)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 926-8318
ALEXANDRA DUMITRESCU
Internal Medicine
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200
PELEG HOROWITZ
Neurological Surgery
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200
SANDEEP GURBUXANI
Pathology (Hematology)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200
DR. NIREN GANDRA M.D.
Internal Medicine
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 702-0240
ALLIE DAKROUB MD MS
Internal Medicine
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 702-1000
SCOTT VASHER MD
Internal Medicine (Pulmonary Disease)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (773) 702-1000
DR. NATHAN CHARLES NOWALK M.D.
Internal Medicine (Pulmonary Disease)
5841 S MARYLAND AVE
CHICAGO, IL 60637
Cook County (888) 824-0200

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 James Ahn's NPI number?

The NPI number for James Ahn is 1457594574. It was assigned to this individual provider in the NPPES registry on April 20, 2009.

Where is James Ahn located?

James Ahn practices at 5841 S Maryland Ave, Chicago, IL 60637. The listed phone number is (888) 824-0200.

What is James Ahn's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Is James Ahn enrolled in Medicare?

Yes. James Ahn is registered in the Medicare PECOS enrollment system.

Which organizations bill Medicare for James Ahn's services?

According to the CMS Revalidation Reassignment List (October 2026 release), James Ahn reassigns Medicare benefits to 2 organizations: The University Of Chicago Medical Center (Chicago, IL) and University Of Chicago (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 James Ahn's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does James Ahn accept?

Health plans from Oscar Health list James Ahn 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 James Ahn was last updated on October 24, 2022. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 4 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.