There is nothing worse than realizing that you a large amount of money in back child support. To avoid these mistakes, it is important to keep in mind certain things:
1) Once the court sets a fixed amount of child support, that amount stays unless and until you go back in to modify your support. Do not, and I repeat, do not, rely on any oral agreements with your ex. If its not in a court order, the Judge can only enforce the court order and you will owe your ex the difference.
2) Just because your employer is not taking out the proper amount of child support does not mean you do not owe it. If its court ordered, it is your responsibility to make up the difference by paying it to the State Disbursement Unit. Otherwise, you are racking up a big arrearage that you will have to pay later.
3) If your support order is for multiple children and they start emancipating, you must go into court to modify your order. Do not assume that you can shave off half or a third unilaterally. The court order stands until the last child emancipates. So until that order is modified, the full amount stands.
4) If your order states that you will pay the State Disbursement Unit, and you decided it would be easier for you, or your ex, to pay her directly, the State may be keeping an accounting and assuming that you owe her all of the money that didn’t go through the State. This mistake can be corrected by showing receipts. However, you better be a hell of a good record keeper to show years of receipts and better be super organized. To avoid this–just pay it through the State.
5) If your maintenance order is for a certain period of time with no termination date, the State will assume that you must continue to pay that amount. As such, if the maintenance is reviewable after 1 year and stopped paying it after that, the State has no way of knowing that your ex never petitioned for the maintenance to continue. As such, it is good practice to file a motion and have a new Uniform Order for Support entered reflecting that change.
In the end, always remember that unless it is court-ordered, you run the risk of having to pay your ex the difference. And there is nothing worse than having to pay back child support even though your children are emancipated.