It is important to know that even though child support is a government program:
The Office of Child Support does not share any client information with the Bureau of Citizenship and Immigration Services (BCIS) —the former Immigration and Naturalization Service (INS).
The child support program is not required to report client immigration status to the Bureau of Citizenship and Immigration Services. Child support workers have confidentiality agreements with the agency and are not supposed to report clients to BCIS/INS. BCIS/INS does not ever seek any information on individuals through the child support system.
Eligibility for child support is not based on citizenship or residency status.
Child support workers are not supposed to ask about the immigration status of clients at any point. Further, child support is not supposed to ask for or collect any documents related to immigration status. There are other forms of identification you can show to the child support office.
If you have other concerns or seek more information, please contact an immigration attorney or legal services in your area. Consultations are often free or on a sliding scale.
Also, you may be able to establish a child support order even if one parent lives in another country. The child support system has agreements with some foreign countries to help enforce child support orders, whether they are established in the U.S. or in the other country. Contact your local child support office to see what they can do if you have such a case.