The Immigration Reform and Control Act of 1986 (IRCA) bars employers from hiring individuals, including illegal aliens, who are not legally entitled to work in the United States. Employers must verify that individuals are eligible to work by obtaining an Employment Eligibility Verification Form, known as Form I-9, and inspecting the required supporting documents at the time of hiring. I-9 forms must be retained for 3 years after the worker is hired or for 1 year after termination, whichever is longer. IRCA prohibits employers from discriminating in hiring, firing, recruiting, or referring on the basis of national origin or citizenship status. It is also illegal to retaliate against an employee who has filed a discrimination charge. This provision applies to employers with four or more employees.