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DR. WILLIAM EZIAL BERGER M.D.
NPI 1538260583
Allergy & Immunology - Allergy in Mission Viejo, CA

Active since September 25, 2006PECOS Enrolled
27800 MEDICAL CENTER RD, SUITE 244, MISSION VIEJO, CA 92691(949) 364-2900(949) 365-0117 Get Directions Write a Review

NPPES record last updated: July 8, 2007. Verified against the NPPES registry weekly; last sync: October 18, 2026.

About Dr. William Ezial Berger M.d. NPPES

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

DR. WILLIAM EZIAL BERGER M.D. (NPI 1538260583) is an individual allergy provider in Mission Viejo, California, licensed in California (C35918) and active in the NPI registry since September 2006. He is enrolled in Medicare PECOS.

NPPES Registry Identity

NPI1538260583
Entity TypeIndividualMale
Primary Taxonomy207KA0200X
Provider Legal NameDR. WILLIAM EZIAL BERGERCredential: M.D.
Location Address27800 MEDICAL CENTER RD, SUITE 244Mission Viejo, CA 92691-6410
Mailing Address27800 Medical Center Rd, Suite 244Mission Viejo, CA 92691-6410 · (949) 364-2900 · Fax (949) 365-0117
Phone(949) 364-2900
Fax(949) 365-0117
Sole ProprietorNo
Enumeration DateSeptember 25, 2006
Last NPPES UpdateJuly 8, 2007
✔ NPI 1538260583 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyAllergy & Immunology · AllergyAllopathic & Osteopathic Physicians
Taxonomy Code207KA0200X
License✔ Licensed in CA · C35918
Definition
A physician who specializes in the diagnosis, treatment, and management of allergies. Source: National Uniform Claim Committee
27800 MEDICAL CENTER RD, Mission Viejo, CA 92691
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Other Identifiers 2

Medicare UPINA87830CA
Medicare ID-Type UnspecifiedW6384CA

Medicare Participation & PECOS CMS

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

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Dr. William Ezial Berger 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 William Berger reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Allergy & Asthma Associates Of Southern Calif Inc
1.0 mi
Allergy
28202 CABOT RD STE 105
Laguna Niguel, CA 92677
  • Reassigned Medicare billing, California enrollment
  • 8 clinicians in this Medicare group
NPI 1164523122 (949) 364-2900
Oso Specialty Infusion, Inc.
14 mi
Infusion Therapy
17175 GILLETTE AVE STE B
Irvine, CA 92614
  • Reassigned Medicare billing, California enrollment
  • 19 clinicians in this Medicare group
NPI 1700305505 (949) 735-6803

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

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.

Reported Quality Measures

Documentation of Current Medications in the Medical Record
Percentage of visits for patients aged 18 years and older for which the eligible professional or eligible clinician attests to documenting a list of current medications using all immediate resources available on the date of the encounter.
100%1,797 patients5/55-star benchmark: 100%
Optimal Asthma Control
Composite measure of the percentage of pediatric and adult patients whose asthma is well-controlled as demonstrated by one of three age appropriate patient reported outcome tools and not at risk for exacerbation
Patients 18-50: 36% · 205 patients
Patients 5-17: 44% · 394 patients
Patients ACT18-50: 36% · 205 patients
Patients ACT5-17: 44% · 394 patients
Patients lowRisk18-50: 100% · 205 patients
41%599 patients
Providers report different measures because they deliver different services; reporting more or less information is not a reflection of quality. Star ratings appear only where CMS assigned them.

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.

THEODORE J. CALIENDO, M.D., A MEDICAL CORPORATION
Pediatrics
27800 MEDICAL CENTER RD, SUITE 204
MISSION VIEJO, CA 92691
Orange County (949) 364-3691
KENNETH K PADDIE A PROFESSIONAL CORP
Otolaryngology
27800 MEDICAL CENTER RD, SUITE 261
MISSION VIEJO, CA 92691
Orange County (949) 364-2555
MEDINA PEDIATRICS, INC.
Pediatrics (Neonatal-Perinatal Medicine)
27800 MEDICAL CENTER RD, SUITE 204
MISSION VIEJO, CA 92691
Orange County (949) 364-3532
REXINGER MEDICAL GROUP, INC.
Family Medicine
27800 MEDICAL CENTER RD, SUITE 461
MISSION VIEJO, CA 92691
Orange County (949) 364-5600
DR. BRETT MICHAEL WERTMAN M.D.
Internal Medicine (Cardiovascular Disease)
27800 MEDICAL CENTER RD, SUITE 222
MISSION VIEJO, CA 92691
Orange County (949) 276-2446
JACKSON MOSES, DDS, INC
Dentist (Oral and Maxillofacial Surgery)
27800 MEDICAL CENTER RD, 238
MISSION VIEJO, CA 92691
Orange County (949) 364-0220
BRITTANY DANIELLE FARMER ACSW
Social Worker (Clinical)
27800 MEDICAL CENTER RD
MISSION VIEJO, CA 92691
Orange County (949) 866-3600
DR. ANDREW CHANG
Dentist (Pediatric Dentistry)
27800 MEDICAL CENTER RD, SUITE 332
MISSION VIEJO, CA 92691
Orange County (949) 364-1171

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 William Berger's NPI number?

The NPI number for William Berger is 1538260583. It was assigned to this individual provider in the NPPES registry on September 25, 2006.

Where is William Berger located?

William Berger practices at 27800 Medical Center Rd Suite 244, Mission Viejo, CA 92691. The listed phone number is (949) 364-2900.

What is William Berger's specialty?

The primary specialty registered for this NPI is Allergy & Immunology, specializing in Allergy, with taxonomy code 207KA0200X.

Is William Berger enrolled in Medicare?

Yes. William Berger is registered in the Medicare PECOS enrollment system.

Which organizations bill Medicare for William Berger's services?

According to the CMS Revalidation Reassignment List (October 2026 release), William Berger reassigns Medicare benefits to 2 organizations: Allergy & Asthma Associates Of Southern Calif Inc (Laguna Niguel, CA) and Oso Specialty Infusion, Inc. (Irvine, CA). 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 William Berger'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 William Berger was last updated on July 8, 2007. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 19 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.