David Forbes, CRNP
David Forbes, CRNP is a Psychiatric/Mental Health Clinical Nurse Specialist in Clarksville, MD, registered under NPI 1164427266. This provider registers 3 separate taxonomy codes, which usually means they practise across more than one recognised specialty. 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 6339 TEN OAKS RD STE 300, Clarksville, MD 21029. 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 |
|---|---|---|
| R113539 | MD | Psychiatric/Mental Health Clinical Nurse… primary |
| R1-3539 | MD | Family Nurse Practitioner |
| R113539 | MD | Family Nurse Practitioner |
| R113539 | MD | Nurse Practitioner |
This provider holds licence R113539 issued in MD. 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 - Nurse Practitioner
- PAC ID
- 6305835612
Enrolled in Medicare 2 times, across 2 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Maryland | I20040511001190 | Practitioner - Nurse Practitioner |
| District of Columbia | I20060425000191 | Practitioner - Nurse Practitioner |
Medicare enrolment is recorded as approved under the provider type Practitioner - Nurse Practitioner. There are 2 separate enrolment records across 2 states (MD, DC). 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.
What Psychiatric/Mental Health covers
Definition to come... NUCC Health Care Provider Taxonomy, code 364SP0808X
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 | |
|---|---|---|---|---|
| 364SP0808X | Psychiatric/Mental Health Clinical Nurse Specialist Psychiatric/Mental Health | R113539 | MD | primary |
| 363LF0000X | Family Nurse Practitioner Family | R1-3539 | MD | |
| 363LF0000X | Family Nurse Practitioner Family | R113539 | MD | |
| 363L00000X | Nurse Practitioner | R113539 | MD |
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 | 1164427266 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jun 15, 2005 |
| Last updated | Nov 24, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | CRNP |
| Practice address |
6339 TEN OAKS RD STE 300 Clarksville, MD 21029 (443) 904-1817 Fax (410) 639-5246 |
| Other identifiers |
407499800
· Medicaid (MD) |
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 | 1 | 6 | 4 | 4 | 2 | 7 | 2 | 6 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 1 | 3 | 4 | 8 | 2 | 5 | 2 | 3 |
Sum = 54 · next multiple of 10 = 60 · check digit = 6 · actual last digit = 6
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.