DR. WILLIAM HEMSLEY MERWIN III M.D.
NPI 1043697600
Student in an Organized Health Care Education/Training Program in Baltimore, MD
NPI Status: Active since May 04, 2015
Contact Information
201 E UNIVERSITY PKWY DEPT OF
BALTIMORE, MD
ZIP 21218
Phone: (410) 554-2284
Fax: (410) 554-2184
NPPES record last updated: June 11, 2025. Verified against the NPPES registry weekly; last sync: July 12, 2026.
Record update history: Jun 11, 2025, Jun 15, 2021, Jan 16, 2019 and 4 more (7 updates tracked since 2017).
- Individual
- Male
- Years of Experience 12
- Student in an Organized Health Care Educ...
- Accepts Medicare Approved Payment
- PECOS Enrolled
About WILLIAM MERWIN
This page provides the complete NPI Profile along with additional information for William Merwin, a primary care provider established in Baltimore, Maryland with a medical specialization in Student In An Organized Health Care Education/training Program and more than 12 years of experience. He graduated from Georgetown University School Of Medicine in 2015. The healthcare provider is registered in the NPI registry with number 1043697600 assigned on May 2015. The practitioner's primary taxonomy code is 390200000X. The provider is registered as an individual and his NPI record was last updated one year ago.
- NPI
- 1043697600
- Provider Name
- DR. WILLIAM HEMSLEY MERWIN III M.D.
- Gender
- Male
- Entity Type
- Individual
- Location Address
- 201 E UNIVERSITY PKWY DEPT OF BALTIMORE, MD 21218
- Location Phone
- (410) 554-2284
- Location Fax
- (410) 554-2184
- Mailing Address
- 201 E UNIVERSITY PKWY BALTIMORE, MD 21218
- Mailing Phone
- (410) 554-2284
- Mailing Fax
- (410) 554-2184
- Medical School Name
- GEORGETOWN UNIVERSITY SCHOOL OF MEDICINE
- Graduation Year
- 2015
- Is Sole Proprietor?
- Yes
- Enumeration Date
- 05-04-2015
- Last Update Date
- 06-11-2025
- Code Navigator
A primary care provider (PCP) like William Merwin sees people with common medical problems. The primary care provider might be a doctor, physician assistant, nurse practitioner or clinic that are usually involved in your long-term care. A PCP might provide preventive care, treat common medical conditions, identify urgent medical problems and refer you to specialists when necessary. Primary care is usually provided in an outpatient facility but if you are admitted to a hospital your PCP may assist in your care. The most common medical conditions seen by primary care providers are: hypertension, upper respiratory tract infections, depression or anxiety, back pain, arthritis, dermatitis, diabetes, urinary tract infections, etc
Location Map
Specialty - Primary Taxonomy
The NPI enumerator requires providers to submit at least one taxonomy code. A taxonomy code is a unique 10-character code that describes the healthcare provider type, classification, and the area of specialization. There could be only one primary taxonomy code per NPI record. For individual NPIs the license data is associated to the taxonomy code.
- Classification
Student in an Organized Health Care Education/Training Program
- Taxonomy Code
- 390200000X
- Type
- Student, Health Care
- License State
- MD
- Taxonomy Description
- An individual who is enrolled in an organized health care education/training program leading to a degree, certification, registration, and/or licensure to provide health care.
Secondary Taxonomies
The provider has reported to the NPI enumerator additional taxonomy codes. Multiple taxonomy codes may represent subspecialties or other areas of specialization the provider maybe licensed to practice.
| No. | Taxonomy Code | Type | Classification / Specialization |
License No. (State) |
|---|---|---|---|---|
| 1 | 207R00000X | Allopathic & Osteopathic Physicians | Internal Medicine | D0091613 (MD) |
Medicare Participation & PECOS Enrollment Status
William Merwin is registered with Medicare and accepts claims assignment, this means the provider accepts the approved amount for the cost of rendered services as full payment. Participating providers may not charge beneficiaries more than the approved amount for their services. Please keep in mind that beneficiaries still have to pay a coinsurance or copayment amount for a visit or service.
William Merwin is enrolled in PECOS and is eligible to order or refer health care services for Medicare patients. The provider is eligible to order or refer: Part B Clinical Laboratory and Imaging, Durable Medical Equipment (DME), a Home Health Agency (HHA) and Power Mobility Devices.
What is PECOS?
PECOS is the online Medicare enrollment management system or Provider, Enrollment, Chain and Ownership System. The PECOS system is a database of providers who have registered with CMS as providers or suppliers. PECOS is the primary source of information about verified Medicare professionals. Providers that want to participate in this program need to enroll in PECOS with their NPI number to avoid denied claims.
Is the provider registered in PECOS? Yes
PECOS PAC ID: 5799185633
What is the PECOS Associate Control ID?
A PAC ID is a unique 10-digit number assigned to an individual or organization healthcare provider in PECOS. The PAC ID is used to link together all the provider information, like tax identification numbers and organizational names. A PAC ID can be connected to multiple Enrollment IDs if an individual or organization has enrolled in PECOS more than once.PECOS Enrollment ID: I20210614002598
What is the Provider Enrollment ID?
The Enrollment ID is a unique alphanumeric 15-digit code assigned to each new provider's PECOS enrollment application. The Enrollment ID is used to link together all the provider enrollment information like enrollment type, state, provider specialty, and reassignment of benefits.Accepts Medicare Assignment? Yes
What does it mean "accepts medicare assignment"?
When a provider accepts Medicare assignment, the provider agrees to be paid directly by Medicare and to accept the payment amount approved by Medicare. Additionally, the provider agrees to not bill patients for more than the Medicare deductible and coinsurance amounts.
A provider who doesn't accept assignment may charge you up to 15% over the Medicare-approved amount. This is known as the limiting charge. You may have to pay this amount, or it may be covered by another insurer.Eligible to Order or Refer Part B Clinical Laboratory and Imaging: Yes
Eligible to Order or Refer Durable Medical Equipment (DMEPOS): Yes
Eligible to Order or Refer a Home Health Agency (HHA): Yes
Eligible to Order or Refer Power Mobility Devices: Yes
Provider Referred Orders for Durable Medical Equipment, Devices & Supplies
The following list reflects the services, supplies or durable medical equipment ordered by this provider to a DME supplier on behalf of patients. The information below is derived from Medicare claims data and reflects the BETOS category, HCPCS code information and the number times each service was submitted under the Medicare fee-for-service program.
Durable Medical Equipment
DME-Oxygen and Supplies (DC000N)
Portable gaseous oxygen system, rental; includes portable container, regulator, flowmeter, humidifier, cannula or mask, and tubing (HCPCS:E0431)
1 DME suppliers used 16 Medicare Claims 16 Services Paid
DME-Oxygen and Supplies (DC002N)
Oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate (HCPCS:E1390)
1 DME suppliers used 25 Medicare Claims 25 Services Paid
Find Provider Hospital Affiliations - Privileges
Doctors and physicians must apply for hospital privileges to treat patients at hospitals. Find out if your doctor has privileges to practice at your preferred hospital by using the hospital affiliation information below based on recent medical claims.
Hospital affiliation is identified through self-reporting data, inpatient, outpatient, physician and ancillary service claims linked by the medical claims NPI number and place of service code. Additionally, to further determine provider hospital affiliation the clinician must have provided services to at least three patients on three different dates in the last 12 months. William Merwin is affiliated with the following medical facilities:
| Hospital Name | Address | Phone | Hospital Type | Overall Rating |
|---|---|---|---|---|
| MEDSTAR FRANKLIN SQUARE MEDICAL CENTER | 9000 FRANKLIN SQUARE DRIVE ROSEDALE, MD 21237 | (443) 777-7850 | Acute Care Hospitals |
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NPI Number Validation
How NPI Validation Works
The NPI validation process uses the ISO-standard Luhn algorithm, a mathematical "handshake", to ensure that a provider's 10-digit ID is authentic and free of common typing errors.
To verify the NPI 1043697600, we treat the final digit (0) as the Check Digit—the target answer we need to reach. The process begins by taking the first nine digits and adding a constant value of 24, which accounts for the "80840" prefix required for all U.S. health identifiers. We then double every other digit starting from the right and sum the individual digits of those results together. For this specific NPI, that total comes to 60. The final step is to find the difference between that total and the next multiple of ten (60 - 60 = 0).
Digit-by-digit view
Use the first nine digits for the calculation. Starting from the right, double every other digit. The last digit is the check digit and is not part of the calculation.
Step 1: Double every other digit from the right
Starting with the rightmost digit of the first nine digits, double every other value. If doubling creates a two-digit number, add those digits together.
Step 2: Add all digits plus the NPI constant
Add the transformed values, the unchanged digits, and the constant 24.
Step 3: Find the amount needed to reach the next multiple of 10
The next multiple of ten after 60 is 60. The difference is the calculated check digit.
Other Providers at the Same Location
The following 20 providers are registered at the same or a nearby location.
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
BALTIMORE, MD 21218
Frequently Asked Questions
The NPI number assigned to this healthcare provider is 1043697600, enumerated as an "individual" on May 04, 2015.
The provider is located at 201 E UNIVERSITY PKWY DEPT OF BALTIMORE, MD 21218 and the phone number is (410) 554-2284.
Student in an Organized Health Care Education/Training Program with taxonomy code 390200000X.
William Merwin is affiliated with: MEDSTAR FRANKLIN SQUARE MEDICAL CENTER.