If your support order or agreement allows you to make such a variation for this purpose, you can deduct the medical expenses. Otherwise, NO. No one is permitted to make a unilateral variation to a court order or legally-binding agreement for *any* reason, unless provisions for such are specifically included in the order or agreement. It is permitted if you agree to such a variation with your ex-spouse. Any such variations should be written down and signed by both parties for the protection of both. If your ex-spouse is on welfare or collecting another social benefit, such as unemployment insurance, it becomes your interim obligation to assume the financial responsibility for your children. You should be compensated for this in the future when your ex-spouse is in a better financial position. While you may feel morally justified in reducing support for non-payment of expenses, as in this case, or for refusal of visitation rights, as also frequently occurs, the court takes a very dim view of such actions. If you are taken to court over this or any related matter, you are quite liable to have your knuckles sharply rapped by the judge. Just remember who is the beneficiary of these payments: your children. The money is not spousal support; it is child support. This is the obligation you assumed when you fathered these children. Some people have difficulty separating spousal support from child support, but it is important that you do so. I will admit it can be a challenge, though. But you should be the best damned father you can, regardless of the situation. However, I would certainly save any documentation that supports any financial claims on your part regarding child support payments, as medical and educational expenses are considered a support obligation. This is particularly true if your ex-spouse was able to pay her share without incurring hardship for the children. She is bound by the same legal obligations as you. Such documentation can be presented in family court in the future, if needed. It may be allowed, in your jurisdiction, to take you ex-spouse to small claims court to recover such expenses. If you can, it is a more cost-effective way of recouping your expenses without incurring the expense of a lawyer in family court. Be aware that any legal action on your part is liable to be regarded as a hostile act. If the amount in question is small, under $500 for example, it is better that you document the circumstances and save this information for future use in any legal actions that either party may undertake, you or your ex-spouse. If it becomes a routine practice for her to avoid such expenses without a legally-acceptable excuse, you have a case for redress and you should take her to court. Those support obligations I mentioned earlier apply to both of you. If she has failed to make any such payments without good cause, she is also in violation of the support order or agreement.