David George Thomassen, MS, LGPC

David George Thomassen is a Mental Health Counselor provider (Counselor) practicing in Frederick, MD, registered in the NPPES registry with NPI 1013338623 since 2013.

✓ Active NPI ✓ Valid NPI checksum Sole proprietor

NPI	1013338623
Entity type	Individual (Type 1)
Name	David George Thomassen
Credential	MS, LGPC
Sex	Male
Practice address	Frederick, MD, 21701
Phone	2405782322
Enumeration date	2013-12-27
Last updated in NPPES	2013-12-27

Street address withheld — NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

Taxonomy code	Specialty	Primary	License	State
101YM0800X	Mental Health Counselor	Primary	LGP3782	MD

Copy-ready billing details

Provider: David Thomassen, MS, LGPC
NPI: 1013338623
Taxonomy: 101YM0800X (Mental Health Counselor)
Address: Frederick, MD, 21701

Other providers at this practice address

NPI	Name	Type	Specialty	Location
1902722408	Kenneth Cann	Individual	Mental Health Counselor	Frederick, MD
1831244136	Catoctin Counseling Center	Organization	Social Worker	Frederick, MD
1831320530	Colleen Felix	Individual	Professional Counselor	Frederick, MD
1023334893	Megan Arbogast	Individual	Psychiatric/Mental Health Nurse Practitioner	Frederick, MD
1003166679	John Mulhern	Individual	Clinical Social Worker	Frederick, MD
1760822944	Maureen Mulhern	Individual	Professional Counselor	Frederick, MD
1699124115	Bradford Wye	Individual	Clinical Social Worker	Frederick, MD
1912567504	Njideka Emenyi	Individual	Psychiatric/Mental Health Nurse Practitioner	Frederick, MD

Verify this record

Cross-check NPI 1013338623 against the authoritative CMS record: view David George Thomassen on the official NPPES registry .

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes — even if the provider moves or changes specialty. Read the full guide or validate an NPI number.

Frequently asked questions

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

What specialty is David Thomassen?

David Thomassen is registered in NPPES with the primary taxonomy of Mental Health Counselor. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2013-12-27.