Child support orders are set based on the financial situation and needs of the children at the time of the order. It is possible that the situation and the child's needs might change as the years go by. When this occurs, a modification of the order is necessary.
You can't modify a child support order for without reason. Instead, there must be a valid reason as to why you're unable to pay what you're currently ordered to. Typically, this has to be due to something like job loss or major change in household income.
If you know you're going to be unable to pay your child support, you need to act quickly. The courts can't take away the arrears, so the sooner you get the petition for modification filed, the sooner you might have some relief. Until then, keep paying whatever support you can because that will also reduce the arrears you owe.
You should also remember that it is possible for the other parent to request a modification. This might be the case if you get a hefty raise and they want more money. In some cases, the other parent might agree to the terms of a modification that you propose, even if it means they get less money. Any modifications that are proposed must be in the best interests of the child because the court will review them before approving the changes.
Because complete compliance with child support orders is critical, you should ensure you understand the terms. Your attorney can help you with this, and they can also explain the process of going through a modification.