Do F-1 students pay Social Security and Medicare (FICA) taxes on campus or OPT jobs?

Generally no, not while you're a nonresident alien exempt individual. F-1 and J-1 students are usually exempt from the 6.2% Social Security and 1.45% Medicare (FICA) payroll taxes on wages from authorized employment, including on-campus jobs, CPT, and OPT, for as long as they remain nonresident aliens under the exempt-individual rules (typically up to five calendar years). If your employer mistakenly withholds FICA during that period, you can request a refund—first from the employer, then via Form 843 if they won't. Once you've used up your exempt years and become a resident alien under the Substantial Presence Test, FICA applies normally going forward. Many students on OPT lose track of this and overpay. Check your pay stubs against your exempt-individual status, and keep documentation of your visa start year to support any refund claim.