NPI Portal NPI Lookup & Verification

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

Marshall Patrick Day, OD

Optometrist in Clinton, OK · enumerated 2006.

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

National Provider Identifier

1588614960

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)
Name Marshall Patrick Day
Credential OD
Sex Male
Practice address Clinton, OK, 73601
Phone (580) 323-5421
Fax (866) 585-2957
Enumeration date May 10, 2006
Last updated in NPPES Jun 28, 2019

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

Taxonomy & licenses

152W00000X Optometrist Eye and Vision Services Providers · License 918 (OK) 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
100763130A Medicaid OK -

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 → Validate an NPI →

Frequently asked questions

What is the NPI number for Marshall Day?
The National Provider Identifier (NPI) for Marshall Day is 1588614960, a Type 1 (individual) record in the CMS NPPES registry.
Where does Marshall Day practice?
The practice location on file with NPPES is in Clinton, OK. Providers can have multiple locations; NPPES lists the primary practice address.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2019-06-28.