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DR. DHEERAJ MAHAJAN M.D.
NPI 1831133693
Internal Medicine in Oak Park, IL

Active since June 15, 2006PECOS EnrolledAccepts Medicare Assignment
101 MADISON ST STE 300, OAK PARK, IL 60302(708) 486-2700(708) 486-2700 Get Directions Write a Review

NPPES record last updated: March 17, 2026. Verified against the NPPES registry weekly; last sync: October 25, 2026.

About Dr. Dheeraj Mahajan M.d. NPPES

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

DR. DHEERAJ MAHAJAN M.D. (NPI 1831133693) is an individual internal medicine provider in Oak Park, Illinois, licensed in Illinois (036106392) and active in the NPI registry since June 2006. He is enrolled in Medicare PECOS, is affiliated with Loyola University Medical Center, and is a graduate of Other (1997).

NPPES Registry Identity

NPI1831133693
Entity TypeIndividualMale
Primary Taxonomy207R00000X
Provider Legal NameDR. DHEERAJ MAHAJANCredential: M.D.
Location Address101 MADISON ST STE 300Oak Park, IL 60302-4210
Mailing Address101 Madison St Ste 300Oak Park, IL 60302-4210 · (708) 486-2700 · Fax (708) 486-2702
Phone(708) 486-2700
Fax(708) 486-2700
Sole ProprietorYes
Medical School CMSOtherGraduated 1997
Enumeration DateJune 15, 2006
Last NPPES UpdateMarch 17, 2026
NPPES CertifiedMarch 17, 2026
✔ NPI 1831133693 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207R00000X
Licenses✔ Licensed in IL · 036106392✔ Licensed in IL · 036-106392
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.
101 MADISON ST STE 300, Oak Park, IL 60302
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Other Identifiers 1

Medicaid036106392IL

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Ambetter Health, Ambetter Health of Delaware, 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 and accepts Medicare assignment

Dr. Dheeraj Mahajan M.d. 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 ID3779476197
PECOS Enrollment IDI20040207000226
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

5

Medicare enrollment records show Dheeraj Mahajan reassigns Medicare billing to 5 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Cimpar Consulting, LLC
Same address
Specialist
101 MADISON ST STE 300
Oak Park, IL 60302
  • Reassigned Medicare billing, Illinois enrollment
  • 17 clinicians in this Medicare group
NPI 1861713216 (708) 486-2700
Cimpar, S.C.
Same address
Internal Medicine
101 MADISON ST STE 300
Oak Park, IL 60302
  • Reassigned Medicare billing, Illinois enrollment
  • Medicare enrollment name: Cimpar Sc
  • 70 clinicians in this Medicare group
NPI 1467496224 (708) 486-2700
Advocate Health And Hospitals Corporation
3.4 mi
General Acute Care Hospital
3435 W VAN BUREN ST
Chicago, IL 60624
  • Reassigned Medicare billing, Illinois enrollment
  • 4,870 clinicians in this Medicare group
NPI 1801838339 (773) 265-7700
Reya Rehab LLC
3.8 mi
Rehabilitation, Comprehensive Outpatient Rehabilitation Facility (CORF)
501 W NORTH AVE
Melrose Park, IL 60160
  • Reassigned Medicare billing, Illinois enrollment
NPI 1952199978 (773) 415-4030
Insight Chicago, Inc.
8.4 mi
Internal Medicine
2525 S MICHIGAN AVE
Chicago, IL 60616
  • Reassigned Medicare billing, Illinois enrollment
  • 354 clinicians in this Medicare group
NPI 1881261006 (312) 567-2000

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 6

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.

Administration of influenza virus vaccine G0008
The administration of the influenza virus vaccine, also known as the flu shot, is a simple procedure to protect against the flu. A healthcare provider injects a small dose of the vaccine into your arm. This stimulates your immune system to produce antibodies, which will help your body fight off the flu if exposed.
2,135 services2,131 patients
Influenza vaccine, inactivated 90653
The Influenza vaccine, inactivated, is a shot given to protect against the flu. It contains killed virus particles that help your body build immunity to the flu. It's recommended annually to keep your protection up-to-date. It's safe for ages 6 months and up.
1,828 services1,828 patients
Administration of pneumococcal, influenza, hepatitis b, and/or covid-19 vaccine inside a patient's home; reported only once per individual home per date of service when such vaccine administration(s) are performed at the patient's home M0201
The Covid-19 vaccine can be administered at your home for convenience and safety. This service is reported once per home, per date, when only the vaccine is given. It's a straightforward process where a medical professional visits your home to give the vaccine.
278 services267 patients
Pneumococcal conjugate vaccine, 20 valent (pcv20), for intramuscular use 90677
The Pneumococcal Conjugate Vaccine (PCV20) is a shot given to protect against 20 types of bacteria that can cause serious infections like pneumonia and meningitis. It's administered through a muscle, usually in the arm. It's important for overall health.
108 services108 patients
Administration of pneumococcal vaccine G0009
The pneumococcal vaccine helps protect against pneumococcal bacteria, which can cause severe infections like pneumonia and meningitis. The vaccine is given as an injection, typically in the arm. It's recommended for infants, older adults, and those with certain health conditions.
105 services105 patients
Influenza vaccine split virus, preservative free 90662
The Influenza Vaccine Split Virus, preservative-free, is a flu shot to protect against the influenza virus. It is made from parts of inactivated flu viruses and doesn't contain preservatives, reducing potential side effects. It helps your body develop immunity to the flu.
17 services17 patients

Hospital Affiliations CMS Care Compare

Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.

Loyola University Medical Center

Acute Care Hospitals · Maywood, IL
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number140276
Location2160 S 1st AvenueMaywood, IL 60153 · Cook County
Emergency services Birthing friendly

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60302 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.

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.

CIMPAR AT HOME, LLC
Home Health
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700
NIRALI PATEL MD, MBA
Internal Medicine (Cardiovascular Disease)
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700
DR. MUJTABA HUSSAIN MBBS
Internal Medicine
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700
CIMPAR DIAGNOSTICS LLC
Radiology (Diagnostic Radiology)
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (773) 849-9406
DR. ANTHONY ABADIR MD
Psychiatry & Neurology (Psychiatry)
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700
RASHIDAH SEMBATYA FNP-C
Nurse Practitioner (Family)
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700
DR. SHANLI PARNIA M.D.
Internal Medicine
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700
TERESITA BERNABE
Nurse Practitioner (Adult Health)
101 MADISON ST STE 300
OAK PARK, IL 60302
Cook County (708) 486-2700

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 Dheeraj Mahajan's NPI number?

The NPI number for Dheeraj Mahajan is 1831133693. It was assigned to this individual provider in the NPPES registry on June 15, 2006.

Where is Dheeraj Mahajan located?

Dheeraj Mahajan practices at 101 Madison St Ste 300, Oak Park, IL 60302. The listed phone number is (708) 486-2700.

What is Dheeraj Mahajan's specialty?

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

Is Dheeraj Mahajan enrolled in Medicare?

Yes. Dheeraj Mahajan 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 Dheeraj Mahajan's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Dheeraj Mahajan reassigns Medicare benefits to 5 organizations: Cimpar Consulting, LLC (Oak Park, IL), Cimpar, S.C. (Oak Park, IL), Advocate Health And Hospitals Corporation (Chicago, IL), Reya Rehab LLC (Melrose Park, IL) and Insight Chicago, Inc. (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 Dheeraj Mahajan's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does Dheeraj Mahajan accept?

Health plans from Ambetter Health, Ambetter Health of Delaware and Oscar Health list Dheeraj Mahajan 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.

Is Dheeraj Mahajan affiliated with any hospitals?

According to CMS data, Dheeraj Mahajan is affiliated with Loyola University Medical Center.

When was this NPI record last updated?

The NPPES record for Dheeraj Mahajan was last updated on March 17, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 7 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.