How to show contempt of court? Wording advice

I can not give you specifics on what to say without seeing the actual wording of the order that says that the parents are to notify the courts of any change in income.  This is not something that I normally see in a child support order.  That being said, for the motion for show cause, you would need to quote the actual wording of the existing order and then in the next portion of the motion you would explain why that has been violated.  It would then be up to the court to determine whether or not the other parent is in violation of the order.  However, this would be a only for contempt to obey and order of the court and would not result in a recalculation of the support amount. Your other option is to file for a motion to modify or amend child support.  When the case is heard, the court can recalculate the child support based on the currrent incomes at the time of the hearing.  There can be an award of the modified amount retroactive to the time of the filing of the petition (or the service on the other parent, which is usually within a few days).  However, you can not request a payment for what you belive to be overpayments prior to the filing for the adjustment. I also suggest you look closely at the guideline calculations and perhaps have a consultation with a child support attorney to make sure that you will get the result you anticipate.  I have often had cases where the non-custodial parent was in your situation, and thought that his child support would be reduced when his child's mother got a new job with a raise, but in actuality the child support amount increased.  Remember that child support is based on a percentage of gross income of both parents and sometimes a smaller percentage of a larger number equals a higher child support obligation.