Depends on how you mean exactly. If your H was laid off from his last, higher paying job and had to take a pay cut to get a new one, it is possible he could get a reduction from the previous higher 28% etc. he's still going to be held to the state standard for the new job at the least. Now if he quit and moved to the new job because he didn't like his old higher paying job, was fired or otherwise "voluntarily" left his higher pay, then no, there's no chance of a reduction.

If it is significantly less, then I would def ask for a modification. If he is already paying the max, and at 28 percent that is the max plus health insurance then the only thing that could happen is it for it to go down, esp if he is making less. The worst that could happen is that he has to continue paying that absurd amount.

And wow! He has to pay for half expenses and half everything else. Does the baby mama work.

It depends on your location, the legal system, and the judge. My nephew had a "flat fee" he paid whether he was employed or not. His parents had to pay his CS a few times because he was unemployed. Someone else I know (different county) had a rate of 25% of his take-home pay. When he took home nothing (unemployed, no unemployment wages), he paid nothing. Crazy, huh?

I see you're in IL. You will have hurdles trying to get away from 28%. The 'half expenses' along with the 'half healthcare' is something your DH had to have agreed to and it is not part of the CS guideline. Those are items he would have negotiated.

What might happen in your case is say DH was making 5000 a month and now he is making 4000 a month because he lost his former job at a manufacturing company that packed up and left the state and/or closed. In this scenario it was no fault of his own making and the next employment he could get per his position skills was at another manufacturing company but this new one doesn't pay as well. He would still pay 28% of his current wage but the CS would be based on his new earnings of $4000 not the older $5000.

That would not get him lower on his other agreements of half expenses healthcare ect. Those would have to go back and be renegotiated. For example, say in the initial agreement he agreed to pay 1/2 of back to school clothing, 1/2 of all extra child activities blah blah. He may not be able to readily afford those generous halves any longer. Kids may have to cut back on the extra activities or something along the lines of one sport a year per kid which is mutually chosen/agreed to by the parents with Dad paying 1/2 of needed equipment,

You also didn't mention how BM and Dh have taxes in their current agreement. If BM has been claiming the kids every year , it's possible to negotiate it into changing the Co to state BM gets even years, Dad gets odd years (if he meets the tax requirements).

Illinois does not take the CP income into factoring CS nor does it take overnights and the like. It is a flat percentage of income based on the NCP.

All he can do is file for an amendment of CS due to significant change of circumstances (the lower paying job) and take his chances before a judge.

It is unlikely that CS will go down however. The income shares CS model and related formulas that most states use a variety of tend to heavily penalize the NCP. When we filed to amend CS the Sperm Idiot always got nailed for ever increasing CS even when his income stayed the same and my wife's went up significantly.

DH should not get his hopes up.

Even being married to the CP for 20+ years I can recognize how screwed most NCPs are. Particularly NCP dads.