It is not illegal for an employer to ask you for your social security number (SSN). HOWEVER you are in no way obligated to provide your SSN.When you receive the worker's Social Security number, file Form W-2c (Corrected Wage and Tax Statement), to show the worker's number. All students in J-1 status are eligible to apply for a Social Security Number without being employed, including students with a doctoral fellowship. To apply for work study jobs at King's College, you must present an original document verifying your Social Security Number. Have them enter their Social Security number in Section 1 as soon as they receive it. Legitimate employers will require you to provide both your SSN and a photo ID when they fill out the I9 form. Department of Homeland Security. 1. It is legal for employers to ask for SSNs on job applications. However, candidates are not obligated to provide it if they feel uncomfortable.