34 C.F.R.  §300.503. Prior notice by the public agency; content of notice.

(a) Notice. (1) Written notice that meets the requirements of paragraph (b) of this section must be given to the parents of a child with a disability a reasonable time before the public agency--

(i) Proposes to initiate or change the identification, evaluation, or educational placement of the child or the provision of FAPE to the child; or
(ii) Refuses to initiate or change the identification, evaluation, or educational placement of the child or the provision of FAPE to the child.