Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Mark T Sontag, M.D.

Q: What is the NPI number for Mark Sontag?

The National Provider Identifier (NPI) for Mark Sontag is 1528060381, a Type 1 (individual) record in the CMS NPPES registry.

Anesthesiology Physician in Eau Claire, WI · enumerated 2005.

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

National Provider Identifier

1528060381

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Registry record

Entity type Individual (Type 1)

Name Mark T Sontag

Credential M.D.

Sex Male

Practice address 1221 Whipple St, Eau Claire, WI, 54703

Phone (715) 838-3311

Enumeration date Aug 11, 2005

Last updated in NPPES May 15, 2014

Taxonomy & licenses

207L00000X Anesthesiology Physician Allopathic & Osteopathic Physicians · License 29393 (WI) 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
31423100	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.

Read the full guide → Validate an NPI →

Frequently asked questions

Where does Mark Sontag practice?

The practice location on file with NPPES is in Eau Claire, WI. Providers can have multiple locations; NPPES lists the primary practice address.

What is the NPI number for Mark Sontag?

The National Provider Identifier (NPI) for Mark Sontag is 1528060381, a Type 1 (individual) record in the CMS NPPES registry.

Other providers at this practice address

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2014-05-15.