Do I need to include my Federal Tax Forms with my Illinois State Tax return?

Helping my son file his taxes for the first time. He is filing for the first time in Illinois and needs to snail mail in his IL-1040. TurboTax only had us print the IL-1040, but do we need to include his electronically filed Federal 1040 in the snail mail as well? I cannot find a direct answer online - or one that makes sense to me at least.