For a child to initially receive special education services an initial evaluation must be done to identify eligibility under specific educational criteria. It must be determined that there is an educational impact as a result of a disability.
Once a child qualifies for special education services an IEP is written based on the needs identified in the evaluation. Going forward a new evaluation must be done a minimum of every three years or sooner if the educational team determines there is a need to reevaluate.
For further information: IDEA Eligibility Determination