If it were me I would explain to the Ex that child support is calculated based on income and doesn't consider expenses, and according to your attorney's calculations child support would likely decrease if she pursued a child support modification. I would also tell her that you have no desire to reduce child support at this time so you have no intention of initiating a child support modification. However, if she feels the need to pursue a child support modification, then she would need to initiate it, and that you will gladly pay whatever the new and more correct child supprt amount is, even if it is a reduction. That will place the ball in her court. I suspect that she would probably do nothing since that would give her less to complain about, and by doing nothing she can continue to feel like a victim. JMHO