As long as you have the court order that stpped the child support , then you will need that to file against the mother, althoug you needed to file to stop the child supprt order the mother knew she was collecting the child support when the child was 18, so your chances of winning are great, you have nothing to lose in filing, you can even ask for the mother to pay for the court cost. I say go for it, to many women get away with this because the fathers usally do not either know their options or just do not feel as you do that you have a chance to win. The judge will tell her she knew that the child support stopped at the age of 18, what she should of done was keep the checks and then returned to you.

That's going to be a coin toss. Your ex is going to blame the state for sending her the money because she'll claim she thought it was back support. The judge may tell her it's no excuse or ask you if you knew you were going to file to stop, did you tell her not to cash the checks. The easiest thing to do is ask child support enforcement to seize her tax returns until the debt is paid. They'd do it to you if given half a chance.

NY state & our divorce decree states support until the age of 21! (as with out older twins that were emancipated at 21 two years ago) The order to stop support was agreed upon by both parties ONLY because our daughter is living on her own. My employer by law had to stay current with payments until a new order was put forth. (of coarse I wanted to stay current as well in case my daughter did return home, no one wins when the account goes into arrears!) The Magistrate told us both in court that family court can not order her mother to pay back the over paid amount because the mother kept the household intact with hopes of the child returning home. It was suggested to me by a friend to take the mother to small claims court for the over paid amount. Just looking to see if anyone out there has gone this route before and if so what the outcome was.
I appreciate any feed back :)

I have to tell you this I was not aware that you owe back child support, this does make a difference so chances are if you have back erarages then you probary will not be able to get any of that money back. There is a difference in over paying and over paying when there is back erarages. so it will be up to the judge, child support probary kept giving the child support to the mother because of the back erarages and if this is true their not going to pay the support back to the father. I have seen this many times over, however you can try.