42 CFR §441.153

1. (a)For an individual who is a beneficiary when admitted to a facility or program, certification must be made by an independent team that—
   1. (1)Includes a physician;
   2. (2)Has competence in diagnosis and treatment of mental illness, preferably in child psychiatry; and
   3. (3)Has knowledge of the individual's situation.
2. (b)For an individual who applies for Medicaid while in the facility of program, the certification must be—
   1. (1)Made by the team responsible for the plan of care as specified in § 441.156; and
   2. (2)Cover any period before application for which claims are made.
3. (c)For emergency admissions, the certification must be made by the team responsible for the plan of care (§ 441.156) within 14 days after admission.