My x has shared custody of our child. He hasn't seen him in over 4 years. He stopped paying child support oner 12 months ago. The IRS law says that he can't claim the child because he has not contributed to his welfare for at least 6 months of the year, yet the court says that he can claim our child every other year. He doesn't have a job, no drivers lic. Can I get the courts to modify the divorce decree?