Ann M. Mass, MD
Internal Medicine Physician · Aspen, CO
Ann M. Mass, MD is an internal medicine physician with a practice address in Aspen, Colorado, and NPI 1598769358, issued on Jun 9, 2005. Check the license (Colorado CO21624, as entered in NPPES) on the Colorado Medical Board; the Medicare figures below come from public CMS files.
- Name
- Ann M. Mass
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License numbers
- CO21624 CO
21624 CO
Self-reported in NPPES; status is on the state search - Practice location
- 225 N Mill St, Aspen, CO 81611
- Phone
- (970) 544-1234
- Enumerated
- Jun 9, 2005
- Record last updated
- Jan 26, 2016 (not updated in 10 years: call before relying on the address or phone)
- Fax
- (970) 544-1310
- Medicaid ID
- 01216241 CO
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 2,046 in Colorado → Look up another NPI →
Also registered at 225 N Mill St
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Ann M. Mass in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersColorado Medical Board
Search for license CO21624Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
15% fewer Medicare Part D claims than the average internal medicine physician in 2024
2,713 Medicare Part D claims for 280 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 17 claims were for opioids.
Most prescribed
- Atorvastatin Calcium218 claims
- Rosuvastatin Calcium142 claims
- Losartan Potassium105 claims
- Levothyroxine Sodium104 claims
- Zolpidem Tartrate74 claims
- Ezetimibe73 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Industry payments in 2024: $15.33
1 payment: food and beverage; the largest payer was Amgen Inc. The 50,334 providers of this specialty with any payment received $1,303.06 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Ann M. Mass among 2,046 internal medicine physician records in Colorado
Ann M. Mass, MD is one of 2,046 internal medicine physician records with a practice address in Colorado. 71% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 90% newer
- In a Medicare fileYes · 71% of these records are
- In the CMS Doctors and Clinicians fileNo · 53% of these records are
- Record last updated2016 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a Colorado practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
9 internal medicine physician records list a practice address in Aspen
They are 9 of the 301 NPPES records with a practice address in Aspen, and 2,046 internal medicine physician records in Colorado.
All 2,046 in Colorado → Every provider in Aspen → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Bryan Gieszl, MDAspen, CO 816111881644649
- Paula Kadison, M.D.Aspen, CO 816111992987838
- Caroline Mears Norris, DOAspen, CO 816111164981270
- Barry Mink, M.D.Aspen, CO 816111720082217
- Carl Schiller, MDAspen, CO 816111053315606
- Eugene Seymour, M.D.Aspen, CO 816111629008057
- Alana Shah, M.D.Aspen, CO 816111538546544
- Susan Zimet, M.D.Aspen, CO 816111063418242
Common questions
What is Ann M. Mass, MD's NPI number?
Ann M. Mass, MD's National Provider Identifier (NPI) is 1598769358, issued on Jun 9, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Ann M. Mass, MD located?
The NPPES record lists a practice address at 225 N Mill St, Aspen, CO, 81611. Phone: (970) 544-1234. Providers update this record themselves, so call before visiting.
How can I verify Ann M. Mass, MD's license?
NPPES lists Colorado license number CO21624, as entered by the provider. Search the Colorado Medical Board at https://dpo.colorado.gov/Medical. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Ann M. Mass, MD prescribe under Medicare Part D?
In 2024, Ann M. Mass, MD had 2,713 Medicare Part D claims for 280 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.