DR. MARGARITA C CASTRO-ZARRAGA M.D.
NPI 1578705679
Family Medicine in Lowell, MA
About Dr. Margarita C Castro-zarraga M.d. NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
DR. MARGARITA C CASTRO-ZARRAGA M.D. (NPI 1578705679) is an individual family medicine provider in Lowell, Massachusetts, licensed in Massachusetts (251722) and active in the NPI registry since April 2009. She is enrolled in Medicare PECOS, is affiliated with United Regional Health Care System, and maintains a secondary practice location in Fitchburg.
NPPES Registry Identity
Specialties & Licenses
Other Names 1
Secondary Practice Location 1
Other Identifiers 1
Accepted 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. Margarita C Castro-zarraga 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
9Medicare enrollment records show Margarita Castro-zarraga reassigns Medicare billing to 9 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Lowell, MA 01852
- Reassigned Medicare billing, Massachusetts enrollment
- 135 clinicians in this Medicare group
Leominster, MA 01453
- Reassigned Medicare billing, Massachusetts enrollment
- 124 clinicians in this Medicare group
Canton, MA 02021
- Reassigned Medicare billing, Massachusetts enrollment
- 113 clinicians in this Medicare group
Springfield, MA 01151
- Reassigned Medicare billing, Massachusetts enrollment
- Medicare enrollment name: Ipc Hospitalists Of New England PC
- 124 clinicians in this Medicare group
Henrietta, TX 76365
- Reassigned Medicare billing, Texas enrollment
- Also billed through NPI 1881175776 (Texas)
- 10 clinicians in this Medicare group
Amarillo, TX 79106
- Reassigned Medicare billing, Texas enrollment
- 150 clinicians in this Medicare group
Plainview, TX 79072
- Reassigned Medicare billing, Texas enrollment
- 217 clinicians in this Medicare group
Lubbock, TX 79401
- Reassigned Medicare billing, Texas enrollment
- 1,338 clinicians in this Medicare group
Lubbock, TX 79401
- Reassigned Medicare billing, Texas enrollment
- 1,439 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
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 5
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
United Regional Health Care System
Acute Care Hospitals · Wichita Falls, TXNorthwest Texas Hospital
Acute Care Hospitals · Amarillo, TXCovenant Hospital Plainview
Acute Care Hospitals · Plainview, TXClay County Memorial Hospital
Critical Access Hospitals · Henrietta, TXComanche County Medical Center
Critical Access Hospitals · Comanche, TXPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 01852 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.
LOWELL, MA 01852
LOWELL, MA 01852
LOWELL, MA 01852
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 Margarita Castro-zarraga's NPI number?
The NPI number for Margarita Castro-zarraga is 1578705679. It was assigned to this individual provider in the NPPES registry on April 3, 2009. The provider is also known as Dr. Margarita Castro Castro M.D..
Where is Margarita Castro-zarraga located?
Margarita Castro-zarraga practices at 161 Jackson St, Lowell, MA 01852. The listed phone number is (978) 937-9700.
What is Margarita Castro-zarraga's specialty?
The primary specialty registered for this NPI is Family Medicine with taxonomy code 207Q00000X.
Is Margarita Castro-zarraga enrolled in Medicare?
Yes. Margarita Castro-zarraga 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 Margarita Castro-zarraga's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Margarita Castro-zarraga reassigns Medicare benefits to 9 organizations: Lowell Community Health Center, Inc. (Lowell, MA), Community Health Connections, Inc. (Leominster, MA), Vantage Healthcare LLC (Canton, MA), Ipc Hospitalists Of New England, P.C. (Springfield, MA), County Of Clay (Henrietta, TX) and 4 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 Margarita Castro-zarraga's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Margarita Castro-zarraga accept?
Health plans from Blue Cross and Blue Shield of Texas list Margarita Castro-zarraga 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 Margarita Castro-zarraga affiliated with any hospitals?
According to CMS data, Margarita Castro-zarraga is affiliated with United Regional Health Care System, Northwest Texas Hospital, Covenant Hospital Plainview, Clay County Memorial Hospital and Comanche County Medical Center.
When was this NPI record last updated?
The NPPES record for Margarita Castro-zarraga was last updated on January 3, 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. Margarita C Castro-Zarraga, M.D. · NPI 1578705679
Family Medicine physician in Lowell, Massachusetts. Individual provider, active in the CMS NPPES registry since April 3, 2009.
## Identity
- **NPI:** 1578705679 (Entity type: Individual)
- **Enumerated:** April 3, 2009
- **Primary specialty:** Family Medicine · taxonomy 207Q00000X
- **State license:** 251722 (Massachusetts)
- **Sole proprietor:** No
## Practice location
- **Address:** 161 JACKSON ST, Lowell, MA 01852-2103
- **Phone:** (978) 937-9700 · **Fax:** (978) 221-6728
## 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:** 9 organizations under Medicare reassignment (form CMS-855R): Lowell Community Health Center, Inc. (NPI 1952307530, Lowell, MA); Community Health Connections, Inc. (NPI 1205566106, Leominster, MA); Vantage Healthcare LLC (NPI 1366903551, Canton, MA); Ipc Hospitalists Of New England, P.C. (NPI 1932516176, Springfield, MA); County Of Clay (NPI 1013357953, Henrietta, TX); and 4 more · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Other, class of 2005
## Record status
- **NPPES last updated:** January 3, 2024
- **Other identifiers:** Medicaid 110028187A (MA)
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Source: [NPI Profile](https://npiprofile.com/npi/1578705679) · Data from the CMS NPPES public registry.