hat is a great question. The difference is that when there is a pending petition for modification, the Court is permitted to go back to the first of the month following the service of the petition rather than when the trial or agreement is reached. If you think about it, this makes sense (which you can’t always say with child support). The idea is simple. If you file for the modification based on a changed circumstance and the other party were simply able to delay the hearing indefinitely, you would lose out on all of those months in between. This way the Court can give you some relief when the case is resolved. This unfortunately does not mean that you can simply pay less in support during this period. You have to pay the full amount of support throughout the pendency of the Petition or you can be subject to enforcement actions. In the prior example Mother failed to act, which resulted in her being unable to go back and get the support from those months before Father filed.