Health Maintenance Organization: how many are there, and how many are in private practice?

National totals

What this specialty covers

(1) A form of health insurance in which its members prepay a premium for the HMO's health services which generally include inpatient and ambulatory care. For the patient, an HMO means reduced out-of-pocket costs (i.e. no deductible), no paperwork (i.e. insurance forms), and only a small copayment for each office visit to cover the paperwork handled by the HMO; (2) A organization of health care personnel and facilities that provides a comprehensive range of health services to an enrolled population for a fixed sum of money paid in advance for a specified period of time. These health services include a wide variety of medical treatments and consults, inpatient and outpatient hospitalization, home health service, ambulance service, and sometimes dental and pharmacy services. The HMO may be organized as a group model, an individual practice association (IPA), a network model or a staff model

Reading the sole-proprietor share

For this specialty, 280 records, or 6.1%, are flagged as sole proprietors in NPPES. The field is self-reported, and for an HMO it is an imperfect proxy for private practice: it does not capture every possible ownership arrangement, while an unflagged record does not by itself show that an organization is not privately operated.

By state

New NPI registrations by year

Counts reflect the year each NPI was first issued, among records still active today. The final year is partial: this data covers through 2026-01-11.

Data notes

• The sole-proprietor field is self-reported by the provider in NPPES and is an imperfect proxy for private practice.
• A sole-proprietor count shown as <11 is suppressed: the true value is below 11, which could include zero.
• An NPI count is a count of records with this primary taxonomy, not a direct census of distinct HMO companies, locations, enrollees, or market share.
• Enumeration year reflects when an NPI was first assigned, not necessarily when an HMO began operating or serving patients.
• Providers are counted once, by their primary taxonomy code only.

Source: CMS National Plan and Provider Enumeration System (NPPES) Data Dissemination file, FOIA-disclosable public data under CMS-6060-N. Aggregated by Hero EMR on 2026-08-03; deactivated NPIs excluded; specialty assigned from the primary taxonomy code (NUCC 25.1). Counts below 11 are suppressed. Individual providers are never published. All provider data pages.

Common questions