As a F-visa holder, you are exempt from FICA for 2013-2017. Starting from January 1st, 2018, once you become a resident for tax purposes by meeting the Substantial Presence Test SPT, you are subject to FICA. When you are a nonresident, your employer should not have withheld your FICA. Please refer to FICA exempt for more information.
If your employer withholds your taxes in error and you are unable to get a full refund of the amount from your employer, file a claim for refund with the Internal Revenue Service on Form 843, Claim for Refund and Request for Abatement
Please see More Form 843 for more information
