Can my husband change child support so that he pays less when kids live with him?

Usually not, as courts figure that the major expenses for the benefit of the children—rent, utilities, mortgage, clothes, and insurance—go on for the custodial parent whether the children are there or not.  However, if you and the children’s father can reach an agreement to reduce his child support payments during vacation periods when they are with him, the Court will probably approve of the child support modification, as the lower payment would probably reflect your savings regarding food and child care expenses, for example.  It is always in the best interests of the children for the parents to agree and be fair to one another, so you might want to consider giving his request some thought.  I would also encourage you to seek the advice of a family law attorney.