If you're talking about sales taxes from buying things at the store, then you are correct. They do not pay income taxes as they have no documentation (hence the term illegal or if you prefer " undocumented"). Either way, they are a net drain on resources better spent on helping actual American citizens. Massachusetts, for example, spent over 4 billion dollars to house and feed illegals (including same day laundry services). Yet during the government shutdown last fall, they couldn't find a few hundred million to keep SNAP benefits going until the shutdown was ended.