"On [Dec. 18, 2013,] the Congressional Budget Office (CBO) released a cost-estimate for the Legal Workforce Act (H.R. 1772). That bill is one part of the House Republican’s immigration reform package that would nationally mandate a version of E-Verify.
CBO notes that many unverifiable employees will be pushed deeper into the underground economy by E-Verify – something that is already occurring in states that mandate its use. Some employers would no doubt continue to pay unverified employees, but would do so off the books and off the radar of the IRS and Social Security Administration. While the government would receive an expected $49 billion in on-budget revenues from new sources of income tax revenue and payroll tax revenue from 2014 to 2023, it would lose $88 billion in off-budget revenue during the same period – mostly from Social Security payroll taxes lost as workers join the underground economy. That’s a $39 billion net loss to revenues due mainly to E-Verify." - Alex Nowrasteh, Dec. 19, 2013.