Back tax on illegal migrants hard to do Requiring illegal immigrants to pay back taxes as a condition of citizenship is a popular idea, but experts on both sides of the immigration debate say it would be extremely difficult to implement. In focus groups and polls on paths to citizenship, if you add conditions such as paying back taxes and learning English, "it gets better response," Camarota says. Many workers file tax returns using an Individual Taxpayer Identification Number issued by the Internal Revenue Service to people who can't get Social Security numbers. Some undocumented ... Read More