Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Thomas K. Marsh, O.D.

Optometrist in Oconomowoc, WI · enumerated 2005 · practices at Thomas K. Marsh, Odsc.

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

National Provider Identifier

1578556239

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Registry record

Entity type Individual (Type 1)

Name Dr. Thomas K. Marsh

Credential O.D.

Sex Male

Practice address 1280 Summit Ave, Oconomowoc, WI, 53066

Phone (262) 567-3214

Fax (262) 567-2449

Enumeration date Aug 29, 2005

Last updated in NPPES Jan 9, 2012

Taxonomy & licenses

152W00000X Optometrist Eye and Vision Services Providers · License 1507 (WI) Primary

OD · Doctor of Optometry: A licensed optometrist providing primary vision care, eye exams, and corrective lenses. About the OD credential

Other identifiers

Identifier	Type	State	Issuer
38564400	Medicaid	WI	-

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

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 Thomas Marsh?

Thomas Marsh is registered in NPPES with the primary taxonomy of Optometrist. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

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Thomas K. Marsh, Odsc Optometrist · Oconomowoc, WI NPI 1649242967

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2012-01-09.