All US employers must properly complete Form I9 for every individual they hire for employment in the United States. This includes citizens and noncitizens.However, a SSN may be needed to process your application when granting items such as Veterans' Preference, Limited. 1. US Social Security Card 2. Not all forms are listed. At that time, you should simply complete a new Form I-9 with your updated SSN and original hire date. U.S. Social Security number (optional unless your company is enrolled in EVerify). Email address (optional). Do not enter an Individual. Taxpayer Identification Number (ITIN) as your Social Security number.