34 CFR §303.322

If, based on the evaluation conducted under § 303.321, the lead agency determines that a child is not eligible under this part, the lead agency must provide the parent with prior written notice required in § 303.421, and include in the notice information about the parent's right to dispute the eligibility determination through dispute resolution mechanisms under § 303.430, such as requesting a due process hearing or mediation or filing a State complaint.