Joan Mcmahon, MD
Joan Mcmahon, MD is an Internal Medicine Physician in Lewistown, MT, registered under NPI 1467403345. 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 408 WENDELL AVE, Lewistown, MT 59457. 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 |
|---|---|---|
| MED-PHYS-LIC-9666 | MT | Internal Medicine Physician primary |
| MED-PHYS-LIC-9666 | MT | Hospitalist Physician |
This provider holds licence MED-PHYS-LIC-9666 issued in MT. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Internal Medicine
- PAC ID
- 9537123229
Medicare enrolment is recorded as approved under the provider type Practitioner - Internal Medicine. This means the provider is enrolled to bill Medicare, though it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
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 2 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 | MED-PHYS-LIC-9666 | MT | primary |
| 208M00000X | Hospitalist Physician | MED-PHYS-LIC-9666 | MT |
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 | 1467403345 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 15, 2006 |
| Last updated | Jun 19, 2024 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
408 WENDELL AVE Lewistown, MT 59457 (406) 535-1502 |
| Mailing address |
310 WENDELL AVE ATT: CLINIC MANAGER Lewistown, MT 59457 |
| Other identifiers |
0029206
(MT) 810536408 · TAX ID # (MT) |
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 | 6 | 7 | 4 | 0 | 3 | 3 | 4 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 4 | 3 | 7 | 8 | 0 | 6 | 3 | 8 |
Sum = 65 · next multiple of 10 = 70 · check digit = 5 · actual last digit = 5
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.