Marc Nash, MD
Marc Nash, MD is a Radiation Oncology Physician in Butte, MT, registered under NPI 1205162922. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 400 S CLARK ST, Butte, MT 59701. 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 |
|---|---|---|
| 20621 | MT | Radiation Oncology Physician primary |
| A100507 | CA | Radiation Oncology Physician |
| 40589 | IA | Radiation Oncology Physician |
Licences are recorded in 3 states: MT, CA, IA. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
Licensed in 3 states
This provider holds licences in 3 states: California, Iowa and Montana. The practice address on file is in Butte, MT, 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
- 20621
- Specialty
- Radiation Oncology 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 Radiation Oncology covers
A radiologist who deals with the therapeutic applications of radiant energy and its modifiers and the study and management of disease, especially malignant tumors. NUCC Health Care Provider Taxonomy, code 2085R0001X
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 | |
|---|---|---|---|---|
| 2085R0001X | Radiation Oncology Physician Radiation Oncology | 20621 | MT | primary |
| 2085R0001X | Radiation Oncology Physician Radiation Oncology | A100507 | CA | |
| 2085R0001X | Radiation Oncology Physician Radiation Oncology | 40589 | IA |
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 | 1205162922 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Oct 30, 2009 |
| Last updated | Aug 6, 2013 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | MD |
| Practice address |
400 S CLARK ST Butte, MT 59701 (406) 723-2621 Fax (406) 723-2470 |
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 | 2 | 0 | 5 | 1 | 6 | 2 | 9 | 2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 2 | 0 | 5 | 2 | 6 | 4 | 9 | 4 |
Sum = 58 · next multiple of 10 = 60 · check digit = 2 · actual last digit = 2
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.