There are many taxes in the US, and illegal immigrants are bound to pay a lot of them, but he was referring to income tax, which they have no way to pay, as it requires a federal ID number (the Social Security Number) and if they had one, they would not be illegal. Many of them have an SSN, but most of the time this is one used by a large number of illegals, so pointing yourself out as being one of the ones using it would be dumb. That said, most people have income taxes deducted from their paychecks, and in some cases, it would probably be hard to prevent that from happening, but, as long as they chose the correct jobs, they could avoid it. Interestingly, income tax filings at the end of the year also include some welfare money for the poor. They can actually be refunded more money than they submitted originally, and I imagine the illegals would often fit in that category.

They still have to pay a variety of sales taxes, which are probably much less than income taxes, but not insignificant.