621491 — HMO Medical Centers
Description
This U.S. industry comprises establishments with physicians and other medical staff primarily engaged in providing a range of outpatient medical services to the health maintenance organization (HMO) subscribers with a focus generally on primary health care. These establishments are owned by the HMO. Included in this industry are HMO establishments that both provide health care services and underwrite health and medical insurance policies.
Exclusions & Cross-References
- Health practitioners or health practitioner groups contracting to provide their services to subscribers of pre-
- paid health plans are classified in Industry 62111, Offices of Physicians; Industry 621210, Offices of
- Dentists; and Industry Group 6213, Offices of Other Health Practitioners; and
- HMO establishments (except those providing health care services) primarily engaged in underwriting and
- administering health and medical insurance policies are classified in U.S. Industry 524114, Direct Health
- and Medical Insurance Carriers.
Overview Facts
| NAICS Code | 621491 |
|---|---|
| Industry Title | HMO Medical Centers |
| SBA Size Standard | $44,500,000 |
| U.S. Establishments | 2,018 (Census CBP, 2023) |
| IRS PBA Code | 621491 (exact match) |
| Sectors Hierarchy | Sector 62 → 621 → 6214 |
| Source / Verified | US Census 2022 NAICS Manual, Census CBP / 2026-06-28 |
Legacy SIC Concordance
Trace the historical mapping chain from the 1987 Standard Industrial Classification (SIC) to the modern 2022 NAICS code format.
- SIC 8011 - Offices and Clinics of Doctors of Medicine (via SIC1987:8011→NAICS1997:621491→2002:621491→2007:621491→2012:621491→2017:621491→2022:621491)
Suggested Product Service Codes (Advisory)
The following Product Service Codes (PSCs) are advisory suggestions aligned with this NAICS code. Note: NAICS and PSC codes map to different dimensions of procurement (industry vs. product/service). There is no official binding 1:1 crosswalk.
- PSC Q701 — Specialized Medical Support
Source: DoD DPCAP PSC Selection Tool (Ingested: 2026-06-29)
Related Resources & Compliance Guides
Further regulatory reference links for NAICS code 621491:
- Sector 62 Directory Hub — List of related industries in the Health Care and Social Assistance sector.
- SIC ↔ NAICS Crosswalk Tool — Look up mappings between legacy SIC codes and modern classifications.
- SBA Size Standards Guide — Complete rules and averaging periods for small business classifications.
- Calculating Annual Receipts Guide — Detailed worked example of revenue calculation rules.
- IRS Principal Business Activity Guide — How NAICS codes map to corporate and entity tax filings.
Related Industries in 6214
Frequently Asked Questions (FAQ)
Is 621491 a valid 2022 NAICS code?
NAICS 621491 is 'HMO Medical Centers', a 2022 U.S. national industry under Sector 62 (Health Care and Social Assistance); the SBA small-business size standard is $44,500,000.
What is the SBA size standard for NAICS 621491?
The SBA small business size standard for NAICS 621491 is $44,500,000 (based on receipts).
What is the legacy SIC code mapping for 621491?
NAICS code 621491 maps to the legacy 1987 SIC codes: 8011 - Offices and Clinics of Doctors of Medicine.