Amends the Illinois Insurance Code. In provisions concerning mental and emotional disorders, provides that every insurer that amends, delivers, issues, or renews group accident and health policies providing coverage for hospital or medical treatment or services for illness on an expense-incurred basis shall provide coverage for the diagnosis and medically necessary treatment (rather than reasonable and necessary treatment and services for) of mental, emotional, nervous, or substance use disorders or conditions. Provides that every insurer that amends, delivers, issues, or renews a group or individual policy of accident and health insurance providing coverage for hospital or medical treatment on or after January 1, 2022 shall provide coverage for medically necessary treatment of mental health and substance use disorders. Provides that an insurer that authorizes a specific type of treatment by a provider shall not rescind or modify the authorization after that provider renders the health care service. Provides that if services for the medically necessary treatment of a mental health or substance use disorder are not available in-network within the geographic and timely access standards set by law or regulation, the insurer shall arrange coverage to ensure the delivery of medically necessary out-of-network services and any medically necessary follow-up services, and the insured shall pay no more in total for benefits rendered than the cost sharing that the insured would pay for the same covered services received from an in-network provider. Provides that an insurer shall not limit benefits or coverage for medically necessary services on the basis that those services should be or could be covered by a public entitlement program. Provides that every insurer shall sponsor an education program, make the program available to other stakeholders, provide clinical review criteria at no cost to providers and insured patients, conduct interrater reliability testing, and achieve interrate pass rates of at least 90% or comply with specified requirements if the 90% threshold is not met. Defines terms.