Jason Day, MD
Jason Day, MD is a Vascular Neurology Physician in Oak Lawn, IL, registered under NPI 1427205038. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty.
Getting there
The practice address on file is 4440 W 95TH ST, Oak Lawn, IL 60453. 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 |
|---|---|---|
| 036-172471 | IL | Vascular Neurology Physician primary |
| ME120414 | FL | Vascular Neurology Physician |
| ME120414 | FL | Neurology Physician |
Licences are recorded in 2 states: IL, FL. 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
- 3072647197
Enrolled in Medicare 3 times, across 3 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Florida | I20141107002066 | Practitioner - Neurology |
| Illinois | I20241227002277 | Practitioner - Neurology |
| Wisconsin | I20251215000610 | Practitioner - Neurology |
Medicare enrolment is recorded as approved under the provider type Practitioner - Neurology. There are 3 separate enrolment records across 3 states (FL, IL, WI). 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 2 states
This provider holds licences in 2 states: Florida and Illinois. The practice address on file is in Oak Lawn, IL, 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
- 036-172471
- Specialty
- Vascular 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 Vascular Neurology covers
Vascular Neurology is a subspecialty in the evaluation, prevention, treatment and recovery from vascular diseases of the nervous system. This subspecialty includes the diagnosis and treatment of vascular events of arterial or venous origin from a large number of causes that affect the brain or spinal cord such as ischemic stroke, intracranial hemorrhage, spinal cord ischemia and spinal cord hemorrhage. NUCC Health Care Provider Taxonomy, code 2084V0102X
All registered taxonomy codes
This provider registers 3 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2084V0102X | Vascular Neurology Physician Vascular Neurology | 036-172471 | IL | primary |
| 2084V0102X | Vascular Neurology Physician Vascular Neurology | ME120414 | FL | |
| 2084N0400X | Neurology Physician Neurology | ME120414 | FL |
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 | 1427205038 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Aug 26, 2008 |
| Last updated | Jan 19, 2026 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
4440 W 95TH ST Oak Lawn, IL 60453 (303) 436-2727 |
| Mailing address |
29373 NETWORK PL Chicago, IL 60673 |
| Other identifiers |
013517400
· Medicaid (FL) 100387633 · Medicaid (WI) P01389312 · Other (FL) |
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 | 4 | 2 | 7 | 2 | 0 | 5 | 0 | 3 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 4 | 4 | 7 | 4 | 0 | 1 | 0 | 6 |
Sum = 52 · next multiple of 10 = 60 · check digit = 8 · actual last digit = 8
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.