Daniel Horn, MD
Daniel Horn, MD is an Internal Medicine Physician in Waltham, MA, registered under NPI 1780903971.
Getting there
The practice address on file is 221 CRESCENT ST STE 202, Waltham, MA 02453. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 251716 | MA | Internal Medicine Physician primary |
| 91509 | SC | Internal Medicine Physician |
| 72732 | AZ | Internal Medicine Physician |
| 036.168528 | IL | Internal Medicine Physician |
| MD.48112 | AL | Internal Medicine Physician |
| MD24268 | HI | Internal Medicine Physician |
| 35C.001303 | OH | Internal Medicine Physician |
| 2024-01822 | NC | Internal Medicine Physician |
| ME166617 | FL | Internal Medicine Physician |
| 70584 | TN | Internal Medicine Physician |
| MD218918 | OR | Internal Medicine Physician |
| 100333 | GA | Internal Medicine Physician |
| U8885 | TX | Internal Medicine Physician |
| DR.0072398 | CO | Internal Medicine Physician |
| MD484408 | PA | Internal Medicine Physician |
Licences are recorded in 15 states: MA, SC, AZ, IL, AL, HI, OH, NC, FL, TN, OR, GA, TX, CO, PA. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Internal Medicine
- PAC ID
- 8224277991
Enrolled in Medicare 14 times, across 14 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Massachusetts | I20130701000464 | Practitioner - Internal Medicine |
| Pennsylvania | I20240510003395 | Practitioner - Internal Medicine |
| Texas | I20240515000756 | Practitioner - Internal Medicine |
| Colorado | I20240515001187 | Practitioner - Internal Medicine |
| Tennessee | I20240516003076 | Practitioner - Internal Medicine |
| Alabama | I20240516003234 | Practitioner - Internal Medicine |
| Florida | I20240520002429 | Practitioner - Internal Medicine |
| Hawaii | I20240521003206 | Practitioner - Internal Medicine |
| Arizona | I20240521003442 | Practitioner - Internal Medicine |
| Illinois | I20240522000427 | Practitioner - Internal Medicine |
| South Carolina | I20240522001987 | Practitioner - Internal Medicine |
| Ohio | I20240530002374 | Practitioner - Internal Medicine |
| Oregon | I20240619001819 | Practitioner - Internal Medicine |
| North Carolina | I20240829001017 | Practitioner - Internal Medicine |
Medicare enrolment is recorded as approved under the provider type Practitioner - Internal Medicine. There are 14 separate enrolment records across 14 states (MA, PA, TX, CO, TN, AL, FL, HI, AZ, IL, SC, OH, OR, NC). Multiple enrolments usually mean the provider bills Medicare from more than one practice location, or has kept an earlier enrolment after moving. Each record carries its own enrolment ID, listed above. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
Licensed in 15 states
This provider holds licences in 15 states: Alabama, Arizona, Colorado, Florida, Georgia, Hawaii, Illinois, Massachusetts, North Carolina, Ohio, Oregon, Pennsylvania, South Carolina, Tennessee and Texas. The practice address on file is in Waltham, MA, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- 251716
- Specialty
- Internal Medicine Physician
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Internal Medicine covers
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. NUCC Health Care Provider Taxonomy, code 207R00000X
All registered taxonomy codes
This provider registers 15 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207R00000X | Internal Medicine Physician | 251716 | MA | primary |
| 207R00000X | Internal Medicine Physician | 91509 | SC | |
| 207R00000X | Internal Medicine Physician | 72732 | AZ | |
| 207R00000X | Internal Medicine Physician | 036.168528 | IL | |
| 207R00000X | Internal Medicine Physician | MD.48112 | AL | |
| 207R00000X | Internal Medicine Physician | MD24268 | HI | |
| 207R00000X | Internal Medicine Physician | 35C.001303 | OH | |
| 207R00000X | Internal Medicine Physician | 2024-01822 | NC | |
| 207R00000X | Internal Medicine Physician | ME166617 | FL | |
| 207R00000X | Internal Medicine Physician | 70584 | TN | |
| 207R00000X | Internal Medicine Physician | MD218918 | OR | |
| 207R00000X | Internal Medicine Physician | 100333 | GA | |
| 207R00000X | Internal Medicine Physician | U8885 | TX | |
| 207R00000X | Internal Medicine Physician | DR.0072398 | CO | |
| 207R00000X | Internal Medicine Physician | MD484408 | PA |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1780903971 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 27, 2010 |
| Last updated | May 26, 2026 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
221 CRESCENT ST STE 202 Waltham, MA 02453 (866) 849-0692 |
| Mailing address |
PO BOX 211699 Eagan, MN 55121 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 7 | 8 | 0 | 9 | 0 | 3 | 9 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 7 | 7 | 0 | 9 | 0 | 6 | 9 | 5 |
Sum = 69 · next multiple of 10 = 70 · check digit = 1 · actual last digit = 1
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.