Child support modification that is agreed between the parties. (The actual amount doesn't have to be agreed upon because it is controlled via a state statute according to a formula.) Make sure that I receive the statutorily required 6 months paystubs and 2 years tax returns from both parties. I have a form for you to complete to see if you are eligible for any deductions. You pay the filing fee. You file it with the court. You are the one who follows procedures to finalize the child support modification.