Understanding F1 Visa Refusal Slots: A Complete Guide The F1 visa is a non-immigrant student visa that permits foreign students to enroll in and completeslots machine gratis their academic programs in the United States. The process of getting this visa can be difficult, though, & getting turned down is one of the most depressing results. An F1 visa refusal slot signifies that a candidate has had their visa application denied, which frequently causes uncertainty & annoyance.