| As such there is nothing legally that you can do to compel him to file a tax return. He just may not be making the required income that would require him to file a tax return!
But then again, it is possible that he is trying to avoid providing child support payments to you as well. If he has a stable job you could go to an Attorney who specializes in Family Law and the Attorney may be able garnish his wages to meet his obligations of providing Child Support payments to you.
Good Luck in your attempts. | 
