If FICA taxes were withheld from an employeeu2019s wages that were not subject to FICA taxes, and the employer will not refund the FICA taxes to the employee, the employee may file an IRS Form 843, to request a refund of FICA taxes. The form and attachments should be mailed to Department of the Treasury, Internal Revenue Service Center, Ogden, UT 84201-0038, USA.A nonresident alien who files Form 843 should typically attach:A copy of the personu2019s Form W-2 to show the amount of FICA taxes withheld, andA copy of the personu2019s U.S. visa, andA copy of the personu2019s Form I-94 or other documentation showing your dates of arrival to the U.S., andA copy of documentation showing the personu2019s permission to work in the U.S. if the person is in either F-1 status or J-1 status, andA copy of documentation showing the personu2019s permission to work in the United States if the person is engaged in either optional practical training (OPT) or employment due to severe economic necessity, andA letter stating that the personu2019s employer would not refund the FICA taxes, or a letter from the employer stating the employer would not refund the FICA taxes to the employee.See the instructions to IRS Form 843 (https://www.irs.gov/pub/irs-pdf/...) for more detailed information.Also see IRS Publication 519 (https://www.irs.gov/pub/irs-pdf/...) for more detailed information, particularly page 44.