Missouri: Ex is threatening to report me for shorting her child support

Here is the situation: I sent my ex a check through the mail for child support before the 15th of the month. She received and about a week later said she lost the check and needs another one. She thinks she washed the check in her pants. She never gave the reminence of the check back, so in order to protect my finances I put a stop payment on that check and deducted the amount from the amount that was suppose to be given to her to cover the amount for the stop payment and provided her a receipt showing the cost of the stop payment. She is threatening to report me for shorting her child support, does she have any ground to stand on?

Since you stopped payment on the check, she did not receive the child support money. You must issue her another check or a money order.

Incidentally, is the child support court ordered? If not, you are under no obligation to give the mother any money.

You are not a financial institution and can not charge your ex for bank fees such as stop payment of a check.

What you could have done was write on the second check in the memo that that amount was a replacement for lost check #. Once she cashed the check she has legally agreed that the original check was lost. If that check was ever cashed by her in the future then you have proof of an additional payment so you can skip one without being behind or you can contact the police about the original check being cashed after it was reported lost and would have proof (her endorsement on the second check) that she committed fraud.

You can not short her child support for bank fees. Sorry but not how it works.