Your ex is required to provide an Income and Expense Declaration anytime a child support modification is filed. There is also a form, called "Request for Income and Expense Declaration after Judgment" that you are entitled to serve once per year. You can find it via google, just search for form FL-396. If you do not believe that your ex will admit this willingly, you may need to subpoena the military. You need a court-issued subpoena (i.e. the judge will have to sign it). Regardless, it may not even be considered as income available for support, so it is best to consult an attorney. Good luck!