David Hahn, MD
David Hahn, MD is a Neurology Physician in Greenwich, CT, registered under NPI 1053625459.
Getting there
The practice address on file is 115 MASON ST STE 1, Greenwich, CT 06830. 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 |
|---|---|---|
| ME134710 | FL | Neurology Physician primary |
| 54629 | CT | Neurology Physician |
| 4301114366 | MI | Neurology Physician |
| 19408 | NH | Neurology Physician |
Licences are recorded in 4 states: FL, CT, MI, NH. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Neurology
- PAC ID
- 7911217724
Enrolled in Medicare 2 times, across 2 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Connecticut | I20151106001648 | Practitioner - Neurology |
| New York | I20170615000578 | Practitioner - Neurology |
Medicare enrolment is recorded as approved under the provider type Practitioner - Neurology. There are 2 separate enrolment records across 2 states (CT, NY). 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 4 states
This provider holds licences in 4 states: Connecticut, Florida, Michigan and New Hampshire. The practice address on file is in Greenwich, CT, 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
- 54629
- Specialty
- Neurology 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 Neurology covers
A Neurologist specializes in the diagnosis and treatment of diseases or impaired function of the brain, spinal cord, peripheral nerves, muscles, autonomic nervous system, and blood vessels that relate to these structures. NUCC Health Care Provider Taxonomy, code 2084N0400X
All registered taxonomy codes
This provider registers 4 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2084N0400X | Neurology Physician Neurology | ME134710 | FL | primary |
| 2084N0400X | Neurology Physician Neurology | 54629 | CT | |
| 2084N0400X | Neurology Physician Neurology | 4301114366 | MI | |
| 2084N0400X | Neurology Physician Neurology | 19408 | NH |
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 | 1053625459 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 28, 2010 |
| Last updated | Oct 28, 2025 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
115 MASON ST STE 1 Greenwich, CT 06830 (203) 276-4464 Fax (203) 276-4468 |
| Other identifiers |
3118697
· Medicaid (NH) |
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 | 0 | 5 | 3 | 6 | 2 | 5 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 1 | 3 | 3 | 2 | 1 | 4 | 1 |
Sum = 41 · next multiple of 10 = 50 · check digit = 9 · actual last digit = 9
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.