Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Ann M Mass, MD

Internal Medicine Physician in Aspen, CO · enumerated 2005 · practices at Ann M. Mass, M.D., P.C..

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

National Provider Identifier

1598769358

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Registry record

Entity type Individual (Type 1)

Name Dr. Ann M Mass

Credential MD

Sex Female

Practice address 225 N Mill St, Ste 116, Aspen, CO, 81611

Phone (970) 544-1234

Fax (970) 544-1310

Enumeration date Jun 9, 2005

Last updated in NPPES Jan 26, 2016

Taxonomy & licenses

174400000X Specialist Other Service Providers · License 21624 (CO) Secondary

207R00000X Internal Medicine Physician Allopathic & Osteopathic Physicians · License CO21624 (CO) 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
01216241	Medicaid	CO	-

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

How do I verify Ann Mass's NPI record?

Cross-check NPI 1598769358 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Is NPI 1598769358 active?

Yes, as of the latest NPPES snapshot, NPI 1598769358 is active (record last updated 2016-01-26).

Other providers at this practice address

Browse all →

William Rodman Surgery Physician · Aspen, CO NPI 1316922289 Martin Manosevitz Clinical Psychologist · Aspen, CO NPI 1689725277 Ann M. Mass, M.D., P.C. Internal Medicine Physician · Aspen, CO NPI 1831388008 Heather Kaplinski Clinical Child & Adolescent Psychologist · Aspen, CO NPI 1912147976 Amy Gendron Acupuncturist · Aspen, CO NPI 1346675261

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2016-01-26.