(A) Before a child‘s eighteenth birthday, the child may provide written authorization to remain under the placement and care responsibility of the department after the child attains age eighteen and the court may conclude that it is in the child’s best interests to remain under the placement and care responsibility of the department after the child’s eighteenth birthday. In such cases, the court’s jurisdiction shall continue until the court issues an order terminating its jurisdiction. In no case may the court’s jurisdiction pursuant to this article continue beyond the child’s twenty-first birthday.

(B) Subject to eligibility criteria established by the department, after attaining age eighteen, a child may enter into a voluntary placement agreement with the department to remain under or return to the placement and care responsibility of the department. The department must develop a transition plan for a child who remains in or returns to the placement and care responsibility of the department.

(C) A voluntary placement agreement terminates within one hundred eighty days after it is executed, unless the court determines that it is in the child’s best interests to remain under the placement and care responsibility of the department.