Section 47SS. (a) For the purposes of this section, the following terms shall have the following meanings unless the context clearly requires otherwise:

”Community-based acute treatment”, 24–hour clinically managed mental health diversionary or step-down services for children and adolescents that is usually provided as an alternative to mental health acute treatment.

”Intensive community-based acute treatment”, intensive 24–hour clinically managed mental health diversionary or step-down services for children and adolescents that is usually provided as an alternative to mental health acute treatment.

”Mental health acute treatment”, 24–hour medically supervised mental health services provided in an inpatient facility licensed by the department of mental health that provides psychiatric evaluation, management, treatment and discharge planning in a structured treatment milieu.

(b) A policy, contract, agreement, plan or certificate of insurance issued, delivered or renewed within or without the commonwealth, which is considered creditable coverage under section 1 of chapter 111M, shall provide coverage for medically necessary mental health acute treatment, community-based acute treatment and intensive community-based acute treatment and shall not require a preauthorization before the administration of such treatment; provided, however, that the facility shall notify the carrier of the admission and the initial treatment plan within 72 hours of admission.