Health Maintenance Organization (HMO)

In the United States, a Health Maintenance Organization (HMO) is a medical insurance group that provides health services for a fixed annual fee. It is an organization that provides or arranges managed care for health insurance, self-funded health care benefit plans, individuals, and other entities, acting as a liaison with health care providers (hospitals, doctors, etc.) on a prepaid basis. The Health Maintenance Organization Act of 1973 required employers with 25 or more employees to offer federally certified HMO options if the employer offers traditional healthcare options. Unlike traditional indemnity insurance, an HMO covers care rendered by those doctors and other professionals who have agreed by contract to treat patients in accordance with the HMO’s guidelines and restrictions in exchange for a steady stream of customers. HMOs cover emergency care regardless of the health care provider’s contracted status.


HMOs often require members to select a primary care physician (PCP), a doctor who acts as a “gatekeeper” to direct access to medical services but this is not always the case. PCPs are usually internists, pediatricians, family doctors, geriatricians, or general practitioners (GPs). Except in medical emergency situations, patients need a referral from the PCP in order to see a specialist or other doctor, and the gatekeeper cannot authorize that referral unless the HMO guidelines deem it necessary. Some HMOs pay gatekeeper PCPs set fees for each defined medical procedure they provide to insured patients (fee-for-service) and then capitate specialists (that is, pay a set fee for each insured person’s care, irrespective of which medical procedures the specialists perform to achieve that care), while others use the reverse arrangement.

“Open access” and “POS” (point of service) products are a combination of an HMO and traditional indemnity plan. The member(s) are not required to use a gatekeeper or obtain a referral before seeing a specialist. In that case, the traditional benefits are applicable. If the member uses a gatekeeper, the HMO benefits are applied. However, the beneficiary cost sharing (e.g., co-payment or coinsurance) may be higher for specialist care. HMOs also manage care through utilization review. That means they monitor doctors to see if they are performing more services for their patients than other doctors, or fewer. HMOs often provide preventive care for a lower copayment or for free, in order to keep members from developing a preventable condition that would require a great deal of medical services. When HMOs were coming into existence, indemnity plans often did not cover preventive services, such as immunizations, well-baby checkups, mammograms, or physicals. It is this inclusion of services intended to maintain a member’s health that gave the HMO its name. Some services, such as outpatient mental health care, are limited, and costlier forms of care, diagnosis, or treatment may not be covered. Experimental treatments and elective services that are not medically necessary (such as elective plastic surgery) are almost never covered.

Other choices for managing care are case management, in which patients with catastrophic cases are identified, or disease management, in which patients with certain chronic diseases like diabetes, asthma, or some forms of cancer are identified. In either case, the HMO takes a greater level of involvement in the patient’s care, assigning a case manager to the patient or a group of patients to ensure that no two providers provide overlapping care, and to ensure that the patient is receiving appropriate treatment, so that the condition does not worsen beyond what can be helped.


HMOs in the USA are regulated at both the state and federal levels. They are licensed by the states, under a license that is known as a certificate of authority (COA) rather than under an insurance license. State and federal regulators also issue mandates, requirements for health maintenance organizations to provide particular products. In 1972 the National Association of Insurance Commissioners adopted the HMO Model Act, which was intended to provide a model regulatory structure for states to use in authorizing the establishment of HMOs and in monitoring their operation.