Illegal immigrants for the most part, they aren’t working under the table. They use fake social security numbers, and pay taxes (FICA) on every dollar they make. At tax time, they do not file, and end up forfeiting billions of dollars in unclaimed returns. As a side note, they also pay rent where they live, and so contribute to the local and state tax coffers that way. They pay sales tax when they buy things, which is also a major contribution. Undocumented workers aren’t masked criminals. They’re just people who want to work.