Federal special education regulations require that at least one year prior to the student reaching age 18 the student and the parent must be informed about the rights that will transfer from the parent to the student upon the student's 18th birthday. See 34 CFR §§300.320(c) and 300.520. The notification provided to both the parent and the student must explicitly state that all rights accorded to parents under special education law will transfer to the 18 year old student and that the parent will continue to receive all the required notices from the school district and will have the right to inspect the student's records, but will no longer make special education decisions for the adult student. (Link)
Federal regulations also require that the IEP developed for the 17 year old student include "a statement that the child has been informed of the child's rights under Part B of the Act that will transfer to the child on reaching the age of majority." See 34 CFR §300.320(c).
When a student turns age 18, all of the decisions-making rights in special education that have been exercised by the parent transfer the adult student, unless
A court has appointed a legal guardian for the student, or
The student indicates that he or she wants to share decision-making with his or her parent (or other willing adult), or
The student indicates that he or she wants to delegate decision making to his or her parent(or other willing adult).
Students have the ability to decide if they will: (1) assume all decision making, (2) share decision making with their parents or (3) the parent(s) guardians(s) will continue to make decisions.