Thomas Johnstone, LLMSW
Thomas Johnstone, LLMSW is a Mental Health Counselor in Muskegon, MI, registered under NPI 1083541114. 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 120 W APPLE AVE, Muskegon, MI 49440. 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
NPPES does not list a state licence number for this record. That is not unusual — organizations and some provider types are not required to file one. Verify current licensure with the relevant state board before care.
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.
What Mental Health covers
Definition to come... NUCC Health Care Provider Taxonomy, code 101YM0800X
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 | |
|---|---|---|---|---|
| 101YM0800X | Mental Health Counselor Mental Health | — | MI | primary |
| 101YA0400X | Addiction (Substance Use Disorder) Counselor Addiction (Substance Use Disorder) | — | MI |
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 | 1083541114 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 5, 2026 |
| Last updated | May 5, 2026 |
| Status | Active |
| Sole proprietor | No |
| Credential | LLMSW |
| Practice address |
120 W APPLE AVE Muskegon, MI 49440 (231) 237-8898 |
| Mailing address |
7321 WHITE RD LOT 135 Muskegon, MI 49442 |
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 | 8 | 3 | 5 | 4 | 1 | 1 | 1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 7 | 3 | 1 | 4 | 2 | 1 | 2 |
Sum = 46 · next multiple of 10 = 50 · check digit = 4 · actual last digit = 4
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.