While the administration has used those numbers to bolster their record on immigration enforcement, advocates say the audits have pushed workers further underground by causing mass layoffs and disrupted business practices.
When the ICE audit letter arrived at Belco Forest Products, management wasn't entirely surprised. Two nearby businesses in Shelton, a small timber town on a bay off Washington state's Puget Sound, had already been investigated.
But the 2010 inquiry became a months-long process that cost the timber company experienced workers and money. It was fined $17,700 for technicalities on their record keeping.
"What I don't like is the roll of the dice," said Belco's chief financial officer Tom Behrens. "Why do some companies get audited and some don't? Either everyone gets audited or nobody does. Level the playing field."
Belco was one of 339 companies fined in fiscal year 2011 and one of thousands audited that year.
Employers are required to have their workers fill out an I-9 form that declares them authorized to work in the country. Currently, an employer needs only to verify that identifying documents look real.
The audits, part of a $138 million worksite enforcement effort, rely on ICE officers scouring over payroll records to find names that don't match Social Security numbers and other identification databases.
The audits "don't make any sense before a legalization program," said Daniel Costa, an immigration policy analyst at the Economic Policy Institute, a Washington, D.C., think tank. "You're leaving the whole thing up to an employer's eyesight and subjective judgment, that's the failure of the law. There's no verification at all. Then you have is the government making a subjective judgment about subjective judgment."