They will take his tax refund if he owes back due child support. He should petition the court to have his child support payments reduced and to excuse any overdue payments. You will need to contact a family law attorney in Jefferson County to help you with this. However. once he files his tax return, it is too late. If you have an income tax refund due you from your earnings, he should request that DHR return it, probably by court order. That may be difficult in actual practice.
I would suggest filing married separately for that reason. It is not too late to amend your returns, you may want to talk to a CPA about that.