[mikeyouse]

Say you're an illegal immigrant working for a factory in Texas. Here's a list of your state tax burden:

http://www.itepnet.org/wp2009/tx_whopays_factsheet.pdf

Illegal immigrants are surely in the lowest 20% bucket. What taxes don't they pay? They rent homes, so they pay property taxes. Their money is spent on clothes and food, so they pay sales taxes. The income taxes that they might not pay are an absolutely minuscule portion of their burden -- literally $11/year on average.

Ever since the I-9's existence, most employers use fake social security numbers for their illegal immigrants. So FICA taxes are removed from their paychecks -- and they'll never get them back in the form of Medicare or Social Security. (Don't take my word for it, here's NYT reporting on SSA's "Earnings Suspense File": http://www.nytimes.com/2005/04/05/business/05immigration.htm...)

Smarter people than myself have looked at this, here's a good example: http://www.itep.org/pdf/undocumentedtaxes.pdf -- Tl;Dr: Illegal immigrants pay a lot of taxes, probably pretty close to the amount they would pay if they were legalized. However, they get far less benefit from their taxes since they don't qualify for most programs.