The I-9 form has three categories of acceptable eligibility verification documents(https://www.uscis.gov/i-9-central/form-i-9-acceptable-documents). List A documents establish both an employee’s identity and their authorization to work in the United States. A U.S. passport is an example of a List A document. List B documents establish an employee’s identity. An example of a List B document is a state-issued identification card. List C documents establish an employee’s authorization to work in the US. An unrestricted Social Security Card is an example of a List C document. Employees must present either one List A document or one document from List B plus one from List C.