Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
William Paul Hartmann III, MD
Psychiatry Physician in Mason, OH · enumerated 2005.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1255318408
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Registry record
Entity type Individual (Type 1)
Name William Paul Hartmann III
Credential MD
Sex Male
Practice address 4075 Old Western Row Rd, Mason, OH, 45040
Phone (513) 536-0600
Fax (513) 536-0609
Enumeration date Dec 29, 2005
Last updated in NPPES Sep 4, 2015
Taxonomy & licenses
2084P0800X Psychiatry Physician Allopathic & Osteopathic Physicians · License 35-079023 (OH) Primary
MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure.
About the MD credential
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| 1841239274 | Other | OH | MEDICARE NPI GROUP NUMBER |
| 2404900 | Medicaid | OH | - |
| 9338635 | Other | OH | MEDICARE GROUP NUMBER |
| 1144401464 | Other | OH | PRACTICE LOCATION NPI GROUP NUMBER |
| 2774985 | Other | OH | MEDICAID GROUP NUMBER |
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.
Frequently asked questions
What is the NPI number for William Hartmann?
The National Provider Identifier (NPI) for William Hartmann is 1255318408, a Type 1 (individual) record in the CMS NPPES registry.
Where does William Hartmann practice?
The practice location on file with NPPES is in Mason, OH. Providers can have multiple locations; NPPES lists the primary practice address.
Other providers at this practice address
Browse all → Carol Dewald Adult Psychiatric/Mental Health Clinical Nurse Specialist · Mason, OH NPI 1891793220 Chris Tuell Professional Counselor · Mason, OH NPI 1508840778 Shannon Jensen Clinical Social Worker · Mason, OH NPI 1811963168 Robin Arthur Clinical Psychologist · Mason, OH NPI 1912961566 Nelson Rodriguez Psychiatry Physician · Mason, OH NPI 1710941018 Brett Dowdy Clinical Psychologist · Mason, OH NPI 1003854712 Jane Marasco Clinical Social Worker · Mason, OH NPI 1336181577 Peter White Counselor · Mason, OH NPI 1467484162
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2015-09-04.