The "Increasing Behavioral Health Treatment Act" aims to significantly expand Medicaid coverage for behavioral health services. It achieves this by removing the long-standing exclusion that prevented federal Medicaid matching funds for medical assistance provided to patients under 65 in an Institution for Mental Diseases (IMD). This change allows states to receive federal reimbursement for care in these facilities. To qualify for this expanded coverage, states must submit a comprehensive plan to the Secretary of Health and Human Services. This plan must outline how the state will achieve increased access to outpatient and community-based behavioral health care , particularly for individuals transitioning from IMDs. It also mandates increased availability of various crisis stabilization services , such as crisis call centers, mobile crisis units, and coordinated community crisis response. The plan must also demonstrate improved data sharing and coordination among physical health, mental health, and addiction treatment providers. Furthermore, states must ensure consistent screening for co-morbid physical health conditions and substance use disorders upon admission to psychiatric hospitals and residential treatment settings, and establish strategies for identifying and engaging individuals experiencing serious mental illness or substance use disorder crises. Finally, the bill requires states to implement utilization review policies to ensure treatment at clinically appropriate levels of care in the least restrictive environment. States must also report annually on costs, utilization, and patient outcomes, including the length of stay in IMDs and the type of outpatient treatment received post-discharge.