William Charles O'callahan Jr, MD - Medicare Emergency Medicine in Holden, MA

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William Charles O'callahan Jr, MD is a medicare enrolled "Emergency Medicine" physician in Holden, Massachusetts. He went to University Of Massachusetts Medical School and graduated in 1990 and has 34 years of diverse experience with area of expertise as Emergency Medicine. He is a member of the group practice Urgent Care Specialists, P.c. and his current practice location is 5 Shrewsbury St Ste D, Holden, Massachusetts. You can reach out to his office (for appointments etc.) via phone at (508) 829-3800.

William Charles O'callahan Jr is licensed to practice in Massachusetts (license number 79001) and he also participates in the medicare program. He accepts medicare assignments (which means he accepts the Medicare-approved amount; you will not be billed for any more than the Medicare deductible and coinsurance) and his NPI Number is 1114964186.

Contact Information

William Charles O'callahan Jr, MD
5 Shrewsbury St Ste D,
Holden, MA 01520-1960
(508) 829-3800
(508) 829-3802

Map and Direction




Physician's Profile

Full NameWilliam Charles O'callahan Jr
GenderMale
SpecialityEmergency Medicine
Experience34 Years
Location5 Shrewsbury St Ste D, Holden, Massachusetts
Accepts Medicare AssignmentsYes. He accepts the Medicare-approved amount; you will not be billed for any more than the Medicare deductible and coinsurance.
  Medical Education and Training:
  • William Charles O'callahan Jr attended and graduated from University Of Massachusetts Medical School in 1990
  NPI Data:
  • NPI Number: 1114964186
  • Provider Enumeration Date: 05/31/2006
  • Last Update Date: 03/16/2023
  Medicare PECOS Information:
  • PECOS PAC ID: 3072692805
  • Enrollment ID: I20080506000317

Medical Identifiers

Medical identifiers for William Charles O'callahan Jr such as npi, medicare ID, medicare PIN, medicaid, etc.
IdentifierTypeStateIssuer
1114964186NPI-NPPES
3125645MedicaidMA

Medical Taxonomies and Licenses

TaxonomyTypeLicense (State)Status
207P00000XEmergency Medicine 79001 (Massachusetts)Primary

Group Practice Association

Group Practice NameGroup PECOS PAC IDNo. of Members
Urgent Care Specialists, P.c.73151984888

Medicare Reassignments

Some practitioners may not bill the customers directly but medicare billing happens through clinics / group practice / hospitals where the provider works. Medicare reassignment of benefits is a mechanism by which practitioners allow third parties to bill and receive payment for medicare services performed by them. William Charles O'callahan Jr allows following entities to bill medicare on his behalf.
Entity NameNewton Wellesley Emergency Medicine Specialist Pc
Entity TypePart B Supplier - Clinic/group Practice
Entity IdentifiersNPI Number: 1346355526
PECOS PAC ID: 7810983996
Enrollment ID: O20040423000237
Entity NameUrgent Care Specialists, P.c.
Entity TypePart B Supplier - Clinic/group Practice
Entity IdentifiersNPI Number: 1902157746
PECOS PAC ID: 7315198488
Enrollment ID: O20121119000614

Medicare Part D Prescriber Enrollment

Any physician or other eligible professional who prescribes Part D drugs must either enroll in the Medicare program or opt out in order to prescribe drugs to their patients with Part D prescription drug benefit plans. William Charles O'callahan Jr is enrolled with medicare and thus, if eligible, can prescribe medicare part D drugs to patients with medicare part D benefits.

Mailing Address and Practice Location

Mailing AddressPractice Location Address
William Charles O'callahan Jr, MD
5 Shrewsbury St Ste D,
Holden, MA 01520-1960

Ph: () -		William Charles O'callahan Jr, MD
5 Shrewsbury St Ste D,
Holden, MA 01520-1960

Ph: (508) 829-3800

Reviews and Comments


Emergency Medicine Doctors in Holden, MA

Dr. Richard Julien Freniere, DO
Emergency Medicine
Medicare: Medicare Enrolled
Practice Location: 5 Shrewsbury St Ste D, Holden, MA 01520
Phone: 508-829-3800    Fax: 508-829-3802
Dr. Donald P Jackel, DO
Emergency Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 5 Shrewsbury St Ste D, Holden, MA 01520
Phone: 508-829-3800    Fax: 508-829-3802
Dr. Peter W Rugg, MD
Emergency Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 5 Shrewsbury St Ste D, Holden, MA 01520
Phone: 508-829-3800    Fax: 508-829-3802
Dr. Allison Nourielle Darvish, DO
Emergency Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 10 Lexington Cir, Holden, MA 01520
Phone: 774-239-8503    
Rock H. Jean-guillaume, D.O.
Emergency Medicine
Medicare: Accepting Medicare Assignments
Practice Location: 5 Shrewsbury St Ste D, Holden, MA 01520
Phone: 508-829-3800    Fax: 508-829-3802

Medicare Program: Medicare is a federal government program which provides health insurance to people who are 65 or older. This program also covers certain younger people with disabilities (who receive Social Security Disability Insurance - SSDI), and people with End-Stage Renal Disease (permanent kidney failure requiring dialysis or a transplant, sometimes called ESRD.

Medicare Assignment: Assignment means that your doctor, provider, or supplier agrees (or is required by law) to accept the Medicare-approved amount as full payment for covered services. Most doctors, providers, and suppliers accept assignment, but you should always check to make sure. Participating providers have signed an agreement to accept assignment for all Medicare-covered services.

NPI Number: The National Provider Identifier (NPI) is a unique identification number for covered health care providers. The NPI must be used in lieu of legacy provider identifiers in the HIPAA standards transactions. Covered health care providers and all health plans and health care clearinghouses must use the NPIs in the administrative and financial transactions adopted under HIPAA (Health Insurance Portability and Accountability Act).

Our Data: Information on www.medicarelist.com is built using data sources published by Centers for Medicare & Medicaid Services (CMS) under Freedom of Information Act (FOIA). The information disclosed on the NPI Registry are FOIA-disclosable and are required to be disclosed under the FOIA and the eFOIA amendments to the FOIA. There is no way to 'opt out' or 'suppress' the NPPES record data for health care providers with active NPIs.