"The IRS indicates that he cannot simply attach a copy of the court order, as the court order is conditional, stating that he can take one child as an exemption if his child support is paid in full by Dec 31 of the preceding year."
"Other than that, his correspondence with me is usually (always) at tax time. This year was no different, I simply wrote him a letter indicating that due to the unpaid medical costs, which by the way, exceed any sort of return that he would receive should he file one of the kids, that I will not sign the IRS form 8332, which would give him permission to do so."
If you failed to offer exemption and he was paid up to date on cs just not medical you will be held in contempt.
Hope this isn't the case but if it is tread lightly.