I read this link that cford posted on the other thread, that appears to be the source of a some stats HY2012 has posted. It's from remarks the director of the Center for Immigration Studies (CIS), a right-wing, anti-immigration organization, was planning to give to Congress:
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://budget.house.gov/imo/media/doc/the_cost_of_illegal_immigration_to_taxpayers.pdf
CFord has already identified some issues and a counter-study with some different numbers. Here are some obvious problems I see with the study finding that undocumented immigrants are a net drain:
--in calculating the amounts of taxes paid by undocumented immigrants, he only included federal income tax, Social Security tax, and Medicaid taxes. This is ignoring, among other things, state and local taxes that undocumented immigrants pay - especially sales tax and property tax.
--In stating their impact on the American economy, the author says: "Illegal immigrants do add perhaps $321 billion to the nation's GDP" but then qualifies it by saying "almost all the increase in economic activity goes to the illegal immigrants themselves in the form of wages." But this makes no sense - the immigrants are spending those wages. They are buying food and housing and clothes and all sorts of other things. The author is clearly just trying to handwave away the huge impact on the economy these immigrants have.
--The author also does not attempt to account for what the consequences would be for the American economy if all of these people were taken out of it. The author repeatedly says, essentially, that it doesn't help to add people who do low-skill, low-wage jobs to the economy because it drags the per capita GDP down. but someone has to do those jobs. There is demand for those jobs that will go unfilled without cheap immigrant labor to do them; the result will be contraction of the American economy and/or higher prices for everything if the cost of work in those industries goes up. We can't simply stop bringing immigrants into the country and assume that means we won't need dishwashers, painters, construction workers, gardeners, hospitality workers, and fruit pickers anymore.
--As I already noted in response to another of HY2012's posts, the author treats welfare benefits provided to the children or other household members of undocumented immigrants the same as providing benefits to the undocumented immigrants themselves. I think this is simply wrong from a methodological standpoint. But in any event, the statistic that a higher percentage of those households use welfare benefits is meaningless if you're not attempting to determine how much per household is actually received. I would be willing to bet that the households led by undocumented immigrants use much less in benefits than the average "non-undocumented" household that receives them, especially because it's so much harder for people who are undocumented to claim many types of benefits.