Mark Letterman, DC, OMD
Mark Letterman, DC, OMD is a provider specialising in Chiropractor in Rehoboth Beach, DE, registered under NPI 1285525543. This provider registers 2 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 70 REHOBOTH AVE, Rehoboth Beach, DE 19971. 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 |
|---|---|---|
| F1-0011109 | DE | Chiropractor primary |
| CT-0010019 | DE | Acupuncturist |
This provider holds licence F1-0011109 issued in DE. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
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 Chiropractor covers
A provider qualified by a Doctor of Chiropractic (D.C.), licensed by the State and who practices chiropractic medicine -that discipline within the healing arts which deals with the nervous system and its relationship to the spinal column and its interrelationship with other body systems. NUCC Health Care Provider Taxonomy, code 111N00000X
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 | |
|---|---|---|---|---|
| 111N00000X | Chiropractor | F1-0011109 | DE | primary |
| 171100000X | Acupuncturist | CT-0010019 | DE |
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 | 1285525543 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 14, 2025 |
| Last updated | Jul 14, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | DC, OMD |
| Practice address |
70 REHOBOTH AVE Rehoboth Beach, DE 19971 (302) 612-1077 |
| Mailing address |
1803 SLAUGHTER STATION RD Hartly, DE 19953 |
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 | 8 | 5 | 5 | 2 | 5 | 5 | 4 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 2 | 7 | 5 | 1 | 2 | 1 | 5 | 8 |
Sum = 57 · next multiple of 10 = 60 · check digit = 3 · actual last digit = 3
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.