You need to speak with an attorney about this matter before you do anything. First, as you correctly intuit, if you can't prove someone's income or assets, it is difficult--not impossible, but difficult--to get the proper level of support set. However, presented properly, this might work to your benefit; if you can show a high standard of living, for example, he may have to pay more than he "should" based on his income (e.g. if you and he were living beyond your means, the court may assume, if there's no other evidence, that that reflects his income). A family or divorce law attorney can help you understand what you may be able to get, how to prove or establish his income, etc.However, second, EVERYONE has to pay federal taxes. If he has not paid them, he has violated the law and is subject to potentially enormous back taxes, interest, and penalties. If this comes to light, it's possibe the IRS would move against him and essentially take much of what might go to you. Also, depending on the circumstances, you could possibly be implicated in his tax evasion as well; you therefore need legal advice before doing anything. You should be able to get support; but it will be trickier, for many reasons, than in other cases. Also, if he has not paid taxes, he has not paid into the social security system, which will short change you when its time to retire. There is much you need to discuss.