Child support

Illinois places no specific time limit on how far back you can collect child support.
It will depend on whether CS was ordered or not.

Illinois law does allow for retroactive Child support at the discretion of the court. There are several factors the court can use to weigh whether retroactive support can be awarded.

Back child support, (i.e. court ordered but unpaid support) can be collected even after the custodial parent has died since it would be owed to that person's estate.