If by most you mean 1/3 - 1/2, then yeah, that happens. Also, even if you use a fake or stolen # to pay Social Security, for instance, if you can prove it was you all those years, you can still collect, after one of our clockwork amnesties. And the ones who use ITINs can and do get refunds from paying income tax. More than that, The Child Tax Credit - a fully REFUNDABLE credit - is claimed by tons of illegals every year and they actually get checks from the IRS, costing us a few billion $ every year. And that's all totally legal too. Likewise, all they gotta do is pop out kids and boom, now they are taking care of gen-u-ine Americans who qualify for WIC and other services, which help out the parents. Frankly our system is used and abused by these guys to a ridiculous degree and that's why my compassion is long since gone, and I'm for automated machine gun turrets along the border.