NPI Portal NPI Lookup & Verification

Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

Mr. William Anthony Mathis, LCSW, CADC

Clinical Social Worker in Clarksville, IN · enumerated 2009 · practices at T Mathis Development LLC.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1639408990

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Registry record

Entity type Individual (Type 1)
Name Mr. William Anthony Mathis
Credential LCSW, CADC
Sex Male
Practice address Clarksville, IN, 47129
Phone (888) 948-6789
Fax (877) 345-3501
Enumeration date Dec 16, 2009
Last updated in NPPES Oct 29, 2018

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

Taxonomy & licenses

101YA0400X Addiction (Substance Use Disorder) Counselor Behavioral Health & Social Service Providers · License 1048 (KY) Secondary
1041C0700X Clinical Social Worker Behavioral Health & Social Service Providers · License 34005676A (IN) Secondary
1041C0700X Clinical Social Worker Behavioral Health & Social Service Providers · License 3320 (KY) Primary
LCSW · Licensed Clinical Social Worker: A social worker licensed for clinical practice including mental-health therapy. About the LCSW credential

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.

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Frequently asked questions

What is the NPI number for William Mathis?
The National Provider Identifier (NPI) for William Mathis is 1639408990, a Type 1 (individual) record in the CMS NPPES registry.
Where does William Mathis practice?
The practice location on file with NPPES is in Clarksville, IN. Providers can have multiple locations; NPPES lists the primary practice address.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2018-10-29.