Illegal tax evasion

I heard Lou Dobbs in passing mention the "high cost of illegal immigration." From what I've read immigrants aren't costing as much as is thought, and certainly not as must as "illegal" tax evasion. Anyone got any info on this?

Update:
Found this Dec. 19, 2003 WaPo ditty from the cheating culture:

IRS documents cited by the GAO indicated that these tax-evasion techniques and others are depriving the Treasury of up to $40 billion in unrealized taxes per year, more than the annual budget for the Department of Homeland Security.

From AskQuestions.org:

Tax fraud is estimated at $311 billion this year, more than the entire budget for Medicare, and more than last year's revenues at Walmart or General Electric. Most cheaters go unpunished. What’s worse, the legal tax system is rigged to favor rich people and large corporations at the expense of ordinary citizens and small businesses. Even when everybody abides by the law, middle-income households pay more taxes than rich ones. And politicians keep handing out tax favors to their campaign contributors – at our expense.

Which of the two is more correct, $40B or $311B I leave to others to sort out.

On the other side, the cost of illegal immigration is discussed here stating that illegal immigration is "creating a net fiscal deficit of almost $10.4 billion, or $2,700 per illegal household."

So, six of one and half a dozen of the other, except that it is citizen doing the cheating rather than immigrants seeking a better life that I find the more reprehensible.