If there are no orders RIGHT NOW, there will not be an order for support entered until he is released. However, if there is an order already in place, DHS, will notify DOC of the inmates obligation. Once an order has been entered, child support CANNOT be abated in Illinois. Incarceration alone is not enough to convince the court you cannot support the children. Any income the inmate has (money earned from the state) is called disposable income as there are no taxes on this money and this money is available to DHS for distribution to the children. Money sent from freinds and relatives is not subject to scrutiny by the courts. Upon his release, if he is not working, there is what is called "Implied Support". This is support received from freinds and family members for the sole purpose of supporting the ex offender. Housing, food, transportation stuff like that. The court WILL enter an order at that time of a minimal amount, usually $20 per month per child.
By the way, if there is an Order of Withholding in place NOW, that amount that they say he can pay is adding up and will NEVER go away unless it is paid. He will need to file a Petition to Modify Support. There is no way around this. The court cannot go back and do away with arrearages. However, the modification will take effect retroactively to date the Motion was FILED with the court. So it is in his best interests to file such motion ASAP! AYou need to convince the court that there has been a substantial change in his ability to pay. That is the requirement. Unfortunately, incarceration does not qualify. Be ready to prove to the court that his incarceration is in no way connected to his divorce ( if there is a divorce) case. It cannot be related at all to his children. They will deny his motion in a heartbeat.
Both times that I was in, I had to pay half of my state pay to DHS. If they know where you are they are gonna get you. No doubt about that. They are killers!
Again, I hope this helps. I know what I had to go through and it sounds like alot but it pays off in the long run.