JAROSLAW JAC MD
NPI 1326029802
Internal Medicine - Hematology & Oncology in Westborough, MA
About Jaroslaw Jac Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
JAROSLAW JAC MD (NPI 1326029802) is an individual hematology & oncology provider in Westborough, Massachusetts, licensed in Massachusetts (238060) and active in the NPI registry since November 2005. He is enrolled in Medicare PECOS, is affiliated with Maine Medical Center, and maintains 2 additional practice locations.
NPPES Registry Identity
Specialties & Licenses 2
Secondary Practice Locations 2
Other Identifiers 2
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
Jaroslaw Jac Md 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
12Medicare enrollment records show Jaroslaw Jac reassigns Medicare billing to 12 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Worcester, MA 01608
- Reassigned Medicare billing, Massachusetts enrollment
- 197 clinicians in this Medicare group
Watertown, MA 02472
- Reassigned Medicare billing, Massachusetts enrollment
- 991 clinicians in this Medicare group
Boston, MA 02215
- Reassigned Medicare billing, Massachusetts enrollment
- 346 clinicians in this Medicare group
Cambridge, MA 02139
- Reassigned Medicare billing, Massachusetts enrollment
- 719 clinicians in this Medicare group
Southbridge, MA 01550
- Reassigned Medicare billing, Massachusetts enrollment
- 68 clinicians in this Medicare group
Methuen, MA 01844
- Reassigned Medicare billing, Massachusetts enrollment
- 258 clinicians in this Medicare group
Lawrence, MA 01841
- Reassigned Medicare billing, Massachusetts enrollment
- 305 clinicians in this Medicare group
Hampstead, NH 03841
- Reassigned Medicare billing, New Hampshire enrollment
- 2,620 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
Keene, NH 03431
- Reassigned Medicare billing, New Hampshire enrollment
- 2,999 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 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.
Hospital Affiliations CMS Care Compare 5
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Maine Medical Center
Acute Care Hospitals · Portland, MEUmass Memorial Health - Harrington Hospital
Acute Care Hospitals · Southbridge, MAAnna Jaques Hospital
Acute Care Hospitals · Newburyport, MAHoly Family Hospital
Acute Care Hospitals · Methuen, MAMemorial Hospital, The
Critical Access Hospitals · North Conway, NHPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 01581 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 19
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
WESTBOROUGH, MA 01581
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 Jaroslaw Jac's NPI number?
The NPI number for Jaroslaw Jac is 1326029802. It was assigned to this individual provider in the NPPES registry on November 10, 2005.
Where is Jaroslaw Jac located?
Jaroslaw Jac practices at 150 Flanders Rd, Westborough, MA 01581. The listed phone number is (508) 870-2222.
What is Jaroslaw Jac's specialty?
The primary specialty registered for this NPI is Internal Medicine, specializing in Hematology & Oncology, with taxonomy code 207RH0003X.
Is Jaroslaw Jac enrolled in Medicare?
Yes. Jaroslaw Jac 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 Jaroslaw Jac's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Jaroslaw Jac reassigns Medicare benefits to 12 organizations: Saint Vincent Physician Services, Inc. (Worcester, MA), Steward Medical Group, Inc (Watertown, MA), Associated Physicians Of Harvard Medical Faculty Physicians At Beth Is (Boston, MA), Cambridge Public Health Commission (Cambridge, MA), Umass Memorial Health-Harrington Hospital Inc (Southbridge, MA) and 7 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 Jaroslaw Jac's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Jaroslaw Jac accept?
Health plans from Ambetter from NH Healthy Families, Anthem Blue Cross and Blue Shield and Harvard Pilgrim Health Care list Jaroslaw Jac 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 Jaroslaw Jac affiliated with any hospitals?
According to CMS data, Jaroslaw Jac is affiliated with Maine Medical Center, Umass Memorial Health - Harrington Hospital, Anna Jaques Hospital, Holy Family Hospital and Memorial Hospital, The.
When was this NPI record last updated?
The NPPES record for Jaroslaw Jac was last updated on July 24, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 2 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.
# Jaroslaw Jac, MD · NPI 1326029802
Hematology & Oncology physician in Westborough, Massachusetts. Individual provider, active in the CMS NPPES registry since November 10, 2005.
## Identity
- **NPI:** 1326029802 (Entity type: Individual)
- **Enumerated:** November 10, 2005
- **Primary specialty:** Internal Medicine - Hematology & Oncology · taxonomy 207RH0003X
- **State license:** 238060 (Massachusetts)
- **Sole proprietor:** No
## Practice location
- **Address:** 150 FLANDERS RD, Westborough, MA 01581-1017
- **Phone:** (508) 870-2222
## 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:** 12 organizations under Medicare reassignment (form CMS-855R): Saint Vincent Physician Services, Inc. (NPI 1013997329, Worcester, MA); Steward Medical Group, Inc (NPI 1629398219, Watertown, MA); Associated Physicians Of Harvard Medical Faculty Physicians At Beth Is (NPI 1497151773, Boston, MA); Cambridge Public Health Commission (NPI 1487603585, Cambridge, MA); Umass Memorial Health-Harrington Hospital Inc (NPI 1790780047, Southbridge, MA); and 7 more · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Other, class of 1990
## Record status
- **NPPES last updated:** July 24, 2026
- **Other identifiers:** Medicaid 139379518 (TX); Medicaid 110081560/A (MA)
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Source: [NPI Profile](https://npiprofile.com/npi/1326029802) · Data from the CMS NPPES public registry.