DR. ANDREW RIGGAN WILLIAMS M.D.
NPI 1275988156
Emergency Medicine in Oak Park, IL
About Dr. Andrew Riggan Williams M.d. NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
DR. ANDREW RIGGAN WILLIAMS M.D. (NPI 1275988156) is an individual emergency medicine provider in Oak Park, Illinois, licensed in Illinois (036158129) and active in the NPI registry since April 2016. He is enrolled in Medicare PECOS, is affiliated with Humboldt Park Health, and is a graduate of University Of Michigan Medical School (2016).
NPPES Registry Identity
Specialties & Licenses
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. Andrew Riggan Williams 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.
Medicare Billing Reassignments
10Medicare enrollment records show Andrew Williams reassigns Medicare billing to 10 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Melrose Park, IL 60160
- Reassigned Medicare billing, Illinois enrollment
- 982 clinicians in this Medicare group
Chicago, IL 60622
- Reassigned Medicare billing, Illinois enrollment
- 21 clinicians in this Medicare group
Chicago, IL 60616
- Reassigned Medicare billing, Illinois enrollment
- 354 clinicians in this Medicare group
Bolingbrook, IL 60440
- Reassigned Medicare billing, Illinois enrollment
- 187 clinicians in this Medicare group
Aurora, IL 60504
- Reassigned Medicare billing, Illinois enrollment
- 116 clinicians in this Medicare group
Harvard, IL 60033
- Reassigned Medicare billing, Illinois enrollment
- 382 clinicians in this Medicare group
Lake Geneva, WI 53147
- Reassigned Medicare billing, Wisconsin and Illinois enrollments
- Also billed through NPI 1598718603 (Wisconsin)
- 271 clinicians in this Medicare group
Rockford, IL 61114
- Reassigned Medicare billing, Illinois enrollment
- 1,375 clinicians in this Medicare group
Freeport, IL 61032
- Reassigned Medicare billing, Illinois enrollment
- 478 clinicians in this Medicare group
Urbana, IL 61801
- Reassigned Medicare billing, Illinois enrollment
- 83 clinicians in this Medicare group
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 3
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.
Hospital Affiliations CMS Care Compare 3
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Humboldt Park Health
Acute Care Hospitals · Chicago, ILJavon Bea Hospital
Acute Care Hospitals · Rockford, ILMercy Health System Corp
Acute Care Hospitals · Janesville, WIPhysician 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.
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.
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 Andrew Williams's NPI number?
The NPI number for Andrew Williams is 1275988156. It was assigned to this individual provider in the NPPES registry on April 28, 2016.
Where is Andrew Williams located?
Andrew Williams practices at 3 Erie Ct, Oak Park, IL 60302. The listed phone number is (708) 763-6747.
What is Andrew Williams's specialty?
The primary specialty registered for this NPI is Emergency Medicine with taxonomy code 207P00000X.
Is Andrew Williams enrolled in Medicare?
Yes. Andrew Williams 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 Andrew Williams's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Andrew Williams reassigns Medicare benefits to 10 organizations: Cepamerica Illinois LLP (Melrose Park, IL), Humboldt Park Health Emergency Medicine, LLC (Chicago, IL), Insight Chicago, Inc. (Chicago, IL), Illinois Emergency Medicine Specialists, LLC (Bolingbrook, IL), Aurora Emergency Physicians, LLC (Aurora, IL) and 5 more organizations, listed in the Medicare section above. 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 Andrew Williams's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
Is Andrew Williams affiliated with any hospitals?
According to CMS data, Andrew Williams is affiliated with Humboldt Park Health, Javon Bea Hospital and Mercy Health System Corp.
When was this NPI record last updated?
The NPPES record for Andrew Williams was last updated on March 19, 2024. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 2 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.
# Dr. Andrew Riggan Williams, M.D. · NPI 1275988156
Emergency Medicine physician in Oak Park, Illinois. Individual provider, active in the CMS NPPES registry since April 28, 2016.
## Identity
- **NPI:** 1275988156 (Entity type: Individual)
- **Enumerated:** April 28, 2016
- **Primary specialty:** Emergency Medicine · taxonomy 207P00000X
- **State license:** 036158129 (Illinois)
- **Sole proprietor:** No
## Practice location
- **Address:** 3 ERIE CT, Oak Park, IL 60302-2519
- **Phone:** (708) 763-6747
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 10 organizations under Medicare reassignment (form CMS-855R): Cepamerica Illinois LLP (NPI 1669758546, Melrose Park, IL); Humboldt Park Health Emergency Medicine, LLC (NPI 1104592120, Chicago, IL); Insight Chicago, Inc. (NPI 1881261006, Chicago, IL); Illinois Emergency Medicine Specialists, LLC (NPI 1003150962, Bolingbrook, IL); Aurora Emergency Physicians, LLC (NPI 1508389628, Aurora, IL); and 5 more · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** University Of Michigan Medical School, class of 2016
## Record status
- **NPPES last updated:** March 19, 2024
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Source: [NPI Profile](https://npiprofile.com/npi/1275988156) · Data from the CMS NPPES public registry.