All individuals who will be working legally in the U.S. must obtain a Social Security Number. F-1 students must establish that they either are approved for Curricular Practical Training (CPT), Optional Practical Training or have secured an on-campus job before being eligible to apply for a SSN.
A Social Security Number (SSN) is a nine-digit number assigned to an individual to identify his/her record of earnings while employed in the United States. Through this number the employer will make contributions to the employee's Social Security accounts which provide for future retirement and disability benefits. The SSN is also used to track wages and report taxes to the Internal Revenue Service.
https://www.ssa.gov/pubs/EN-05-10181.pdf
Apply for a Social Security Number
We suggest that you wait for 48 hours after reporting to your school before you apply for a Social Security number. This waiting will help ensure that your immigration status is verfied with the Department of Homeland Security (DHS).
Applications for an SSN must be submitted in person to a Social Security Office. To find the office closest to you, please go to the Social Security Administration Office Locator.
There is no fee for applying for an SSN. However, you must present original documents to establish your identity, immigration status, eligibility to work in the United States, and your current U.S. address. Notarized photocopies are not accepted and the originals will be returned to you once they are reviewed by the interviewer.
You should bring the following documents with you: