Last week, U.S. Immigrations and Custom Enforcement (ICE) told 652 employers their I-9 forms were being audited. That’s more than the number of audits ICE conducted in the entire previous fiscal year. In addition to I-9s, many of the audits will also include subpoenas for EINs, payroll records and correspondences with the Social Security Administration regarding no-match letters.

The nationwide inspection follows an April announcement that ICE planned to focus the majority of its resources on prosecuting employers who hire illegal immigrants.

The list of companies being audited hasn’t been released. ICE has described the effort as a “first step,” meaning there will likely be more mass inspections in the near future.

What should companies managers do if they get a Notice of Inspection (NOI) from the feds?

Preparation is key. Employers must act quickly — the NOIs generally require HR to turn over all I-9s within three business days.

If I-9 records don’t pass muster with ICE, the agency could launch a criminal investigation. But even if there are no criminal charges, employers could face civil fines for faulty record-keeping.