New math

Prior to my divorce, the crazy man and I had an outstanding tax debt from a year in which he chose not to pay his taxes. Since our separation, all of my tax returns have gone directly towards that debt and we had an understanding that at some point this would result in my overpaying my half of the remaining debt. Every month I send an accounting report of how much I have overpaid and the usual response, if I get any at all, is that he will send me his accounting shortly (this has been going on for one year). I finally got him to accept that we needed to discuss a repayment schedule, I made some creative ideas, he was favorable, then nothing more was said until yesterday. Yesterday, I got the new math. For some reason, he felt he was owed reimbursement for a year in which we have no previous agreement on, in fact, we do have an agreement that states "from X date forward" and that is the date I have based my accounting on. In his new math, I would owe him money! Very clever.