All immigrants with authorization to work in the United States may apply for a social security number and card from their local Social Security Administration office. Undocumented immigrants without employment authorization are not eligible for social security numbers, but may still apply for a Taxpayer ID Number from the Internal Revenue Service, which they can use to file and track their federal income taxes.

No. Employers are legally barred from asking questions related to certain topics during an interview. Restricted topics include your citizenship status, disabilities, sexual orientation, religion, family plans, national origin, etc. If an employer asks you about your immigration status or history, that question is in violation of the law, and you are not required to answer it. Instead, say that you are not required to answer the question, and move on to a different topic.

However, employers are required to verify the identity and employment eligibility of all employees hired after November 6, 1986. They do this by completing the Employment Eligibility Verification (I-9) Form. They must review documents showing the employee's identity and employment authorization. The law prohibits employers from rejecting valid documents. Employers can’t ask for more documents—beyond what is already legally required for employment eligibility verification—just because of an employee's citizenship status or national origin. For example, an employer cannot require only individuals the employer perceives as "foreign" to verify their employment eligibility, or produce specific documents (like the employee's "green card" or Employment Authorization Documents). Employees choose which of the permitted documents they show for employment eligibility verification. As long as the document looks reasonably genuine, and relates to the employee, it should be accepted.

The Immigration Reform and Control Act of 1986 (IRCA) is legislation Congress passed, intending to curb unlawful immigration to the United States. Among other things, the law provides for sanctions against employers who demonstrate a pattern or practice of hiring undocumented workers. IRCA also led to the creation of Form I-9, and requires employers and the job applicant to complete the form at the time of hiring.