You must comply with immigration and employment regulations to conduct any formal government audit or site visit. Ensure that all records, including completion by current employees of I-9 forms, documentation supporting any employment verification, and employee eligibility files, are accurate and updated. Perform regular audits on your files to make them full and compliant with both USCIS and the DOL requirements. 

Have internal procedures in place for tracking work authorization status and expiration for all employees, including foreign nationals. Subject your HR and management personnel to training on compliance with procedures and the requisite handling of inquiries from government entities in anticipation of site visits. Document in detail your recruitment process, employee categorization, and any visa sponsorship efforts. 

Ensure your business uses E-Verify as required and that all I-9 forms are properly filled out, signed, and stored. In the case of audits, have an immigration attorney or compliance officer on hand to guide you through the process to mitigate some risks and deal with problems promptly. Finally, maintain clear documentation for any changes in the status of employees or job assignments, and always cooperate with government inspectors, providing the requested documents in a timely and organized manner.