My daughter has a genetic condition and needed an IEP. The middle school she attended would not give her an evaluation until we indicated we knew they were legally required to evaluate her and they should consider this an official request.
All my previous requests were rebuffed as they tried to steer her towards a 504 plan (504 is not legally binding).
I had to pay to have her evaluated by a Pediatric Neuropsychologist (about $500, despite my excellent American Insurance). He diagnosed ADHD and referred to a Neurologist who found nothing, but referred to an MRI, which found stroke damage, then we were referred to a geneticist who identified her mitochondrial disease and put us into a Pediatric Developmental office.
Finally we got some resources that helped us navigate the school issues to get her IEP.
It was so much time, money, and effort.