What type of insurance coverage does a health maintenance organization (HMO) typically require?

Health Maintenance Organizations (HMOs) typically require a referral for specialty services. This system is designed to manage patient care by making primary care physicians (PCPs) the first point of contact for patients. The PCP coordinates the patient’s overall healthcare and must provide a referral for any specialty services, which helps control costs and ensures that care is necessary and appropriate. This referral process allows the HMO to maintain a network of providers and manage healthcare services more efficiently, aligning with the HMO's emphasis on preventive care and cost-effectiveness.

In contrast, other types of insurance plans, such as Preferred Provider Organizations (PPOs), often allow patients more freedom to see specialists without needing a referral. The other answer choices suggest levels of access or approval that do not reflect the structure and requirements typically associated with HMOs.