What is a Social Security number (SSN)?

A Social Security number (SSN) is a unique number used to identify residents in the United States. YSSN Number ou need an SSN to work in the United States and file taxes. The SSN is valid for life, so you only need to apply once. If you are a new F-1 or J-1 student, wait 30 days after the I-20/DS-2019 program start date before applying for an SSN. If you are a J-1 Scholar, please wait 16 days after submitting the arrival confirmation before applying for an SSN.