I just got a letter from the department of child support saying that child support may have been overpaid. If you don't want to read the whole story, the quick question:
There is an existing court order by agreement (we said X amount in MSA, judge signed it, made it an order - wasn't by calculator or judge decision). He thinks he should be paying lower. but there has never been modification by the court. Yesterday I got a letter saying there may have been overpayment. Question: am I worrying for nothing?

Here's the history:

4 years ago, we divorced by MSA (marital settlement agreement in CA). We agreed on the amount, it was approved by the court, and ordered.

He's been whining about lowering the support for years. Closest we ever came last year was when I did all the work to fill out a stipulation form, we both signed it, tried to submit it, and it was rejected by the court because it was on the wrong "form". I filled out the right forms, but then my ex changed a bunch of information that we hadn't agreed on, didn't provide his half of the filing fees, and didn't provide his information to be submitted with the forms. And this is was all for his benefit too (lowering support). So, I wasn't going to try a third time and basically hunt him down to sign paperwork that benefits him!

Now, he's filed out all the paperwork, emailed it to me last week, and I got a letter last night at an old address that they might come after me for replayment.

My question: how can what he paid me in accordance with a court order by considered an overpayment if all this time it's ordered and there hasn't been a change by court order? I've agreed in the past to change it, but nothing has been finalized by the court.

To make matters worse, we've since moved out of state (in my MSA permission that I can). Not in CA anymore, not there in person to fight it. Seeing a local attorney on Thursday to see if we can transfer the case to the state that we're now a resident of since the child in question also has special needs and school/providers are in this state.

But it can someone give me some advice and alleviate my insane worrying? Again, main question: can you "overpay" an existing court order?

First, if he remains in CA, you stand little chance of moving the case.

Second, if the overpayment is based on the fact that the agreed on payment was more than the court would have calculated, I don't see him winning this since he signed the agreement.

But one can't predict what a court will do and we don't know exactly what grounds he is using. You need to fight it on the grounds that the amount was agreed to by all parties. You will probably need to retain an attorney to represent you in CA, especially if he has an attorney. You can probably arrange to appear by telephone. You may also be able to counter sue him for your court costs.

Did he file something without you knowing about it? Also you filing a stipulation isn't enough to do anything. You would have to file for modification. Then if the amount is agreed upon and not a calculation of the dissomaster then that is when a stipulation would be filed and entered into as agreed upon.

If the amount never went through the modification process then there is nothing to complain about.