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WILLOWDALE INTERNAL MEDICINE ASSOCIATES LLC
NPI 1649300161
Internal Medicine in Kennett Square, PA

Active since March 06, 2007CLIA 39D0993682 · Waiver
127 W STREET RD, SUITE 101, KENNETT SQUARE, PA 19348(610) 444-1212(610) 444-3633 Get Directions Write a Review

NPPES record last updated: February 17, 2015. Verified against the NPPES registry weekly; last sync: November 01, 2026.

About Willowdale Internal Medicine Associates Llc NPPES

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

WILLOWDALE INTERNAL MEDICINE ASSOCIATES LLC (NPI 1649300161), doing business as Karl Zimmerman Md Llc, is a healthcare organization registered as an internal medicine in Kennett Square, Pennsylvania and active in the NPI registry since March 2007. The organization holds a CLIA Waiver certificate valid through November 20, 2027 and lists Karl A Zimmerman, Owner, as its authorized official.

NPPES Registry Identity

NPI1649300161
Entity TypeOrganization
Primary Taxonomy207R00000X
Legal Business NameWILLOWDALE INTERNAL MEDICINE ASSOCIATES LLC
Location Address127 W STREET RD, SUITE 101Kennett Square, PA 19348-1698
Mailing Address127 W Street Rd, Suite 101Kennett Square, PA 19348-1698 · (610) 444-1212 · Fax (610) 444-3633
Phone(610) 444-1212
Fax(610) 444-3633
Organization SubpartNo
Authorized OfficialKarl A ZimmermanOwner · (610) 444-1212
Enumeration DateMarch 6, 2007
Last NPPES UpdateFebruary 17, 2015
✔ NPI 1649300161 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207R00000X
License✔ Licensed in PA · MD056655L
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.
127 W STREET RD, Kennett Square, PA 19348
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Other Names 1

Former Legal Business NameKarl Zimmerman Md Llc

Other Identifiers 2

Medicare UPING27893PA
Medicare ID-Type Unspecified067390PA

Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Willowdale Internal Medicine Associates Llc is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Clinicians Billing Medicare Through This Organization

2

Medicare enrollment records show 2 clinicians reassign Medicare billing to Willowdale Internal Medicine Associates LLC, which bills Medicare for the services they deliver. Of these, 1 practice at this address and 2 within 10 miles. They are listed nearest first.

Clinicians, nearest first (2)

Michele Zimmerman, C.R.N.P.
Nurse Practitioner
NPI 1730332768
127 W STREET RD SUITE 101
Kennett Square, PA 19348
(610) 444-1212
✔ PECOSSame address
Karl Zimmerman, MD
Internal Medicine
NPI 1154439966
127 W STREET RD SUITE 101
Kennett Square, PA 19348
(610) 444-1212
✔ PECOS✔ Accepts Medicare0.5 mi

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

CLIA Laboratory Certificates CMS CLIA

Laboratory certificates issued under the Clinical Laboratory Improvement Amendments (CLIA) program, which sets federal quality standards for human laboratory testing in the United States. There is no official CMS crosswalk between CLIA and NPI numbers; these certificates are associated with this NPI by matching facility names, locations and phone numbers in the CMS CLIA registry.

Certificate of Waiver 39D0993682

Willowdale Internal Medicine Associates · Kennett Square, PA
Active · expires Nov 20, 2027
CLIA Number39D0993682
Laboratory TypePhysician Office
Certificate Effective DateNovember 21, 2025
Certificate Expiration DateNovember 20, 2027
Laboratory DirectorDr. Karl Zimmerman
Laboratory Phone(610) 444-1212
Laboratory LocationWillowdale Internal Medicine Associates127 W Street Road Suite 101, Kennett Square, PA 19348
CLIA data matches this NPI record on: Address Name Phone
This certificate is issued to a laboratory to perform only waived tests.

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 Willowdale Internal Medicine Associates LLC's NPI number?

The NPI number for Willowdale Internal Medicine Associates LLC is 1649300161. It was assigned to this organization in the NPPES registry on March 6, 2007. The provider was formerly known as Karl Zimmerman MD LLC.

Where is Willowdale Internal Medicine Associates LLC located?

Willowdale Internal Medicine Associates LLC is located at 127 W Street Rd Suite 101, Kennett Square, PA 19348. The listed phone number is (610) 444-1212.

What is Willowdale Internal Medicine Associates LLC's specialty?

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

Is Willowdale Internal Medicine Associates LLC enrolled in Medicare?

Yes. Willowdale Internal Medicine Associates LLC is registered in the Medicare PECOS enrollment system.

How many clinicians bill Medicare through Willowdale Internal Medicine Associates LLC?

According to the CMS Revalidation Reassignment List (October 2026 release), 2 clinicians reassign their Medicare billing to Willowdale Internal Medicine Associates LLC, in Internal Medicine and Nurse Practitioner. A 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 the clinician's services. Of these, 1 practice at this address and 2 within 10 miles. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Does Willowdale Internal Medicine Associates LLC hold a CLIA laboratory certificate?

Yes. A Certificate of Waiver (number 39D0993682) is associated with this NPI, valid through November 20, 2027. CLIA certificates authorize laboratory testing under the federal Clinical Laboratory Improvement Amendments program.

When was this NPI record last updated?

The NPPES record for Willowdale Internal Medicine Associates LLC was last updated on February 17, 2015. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 11 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.