Dude! I had a same problem, when I was doing my internship. They deducted SS(FICA) tax, then later I googled IRS webiste and found that people are in F-1 status are exempted from SS(FICA) and medicare tax. Reason! you are not going to get return benefit from it. You might want to google it and show that to your employer, human resources or auditor whoever responsible. I am 100% sure you don't need to pay those taxes, if you had paid already, ask them to refund or if they don't agree, then you can claim you tax(FICA) return while filing your tax return form. GOOD LUCK!