Employers who do hire undocumented workers can face important legal and also financial consequences under U.S. immigration law. Hiring unauthorized workers can result in civil fines, as well as penalties, and even criminal charges if a pattern of violations happens to be found. Employers are then required to fully verify work authorization by using Form I-9 for all of their employees and, in some other cases, participate in the E-Verify system so as to confirm employment eligibility. 

Failure to properly complete or retain many I-9 forms can lead to further penalties. Deliberately accepting fraudulent documents, misclassifying employees as independent contractors so as to evade compliance, or even engaging in labor exploitation can result in harsher fines, legal action, and disqualification from federal contracts. To avoid liability, businesses should implement certain compliance programs, conduct periodic internal audits, and seek legal guidance when necessary.