Foreign scholars who are planning a short term-visit to Tsinghua (such as for academic exchange or to attend an academic conference) for a duration of less than 3 months without salary are generally required to apply for an F Visa before entry into China. Since the maximum stay under an F Visa is usually 90 days, applicants for this visa need to have a clear idea about their intended entry date and the duration of their intended stay in China. After the host department/school/institution of Tsinghua University submits the application form to ISSC，ISSC will issue the Invitation Letter of Duly Authorized Unit, which is required to apply for an F Visa. This application process generally takes 3 to 5 working days. The host department and the applicant are strongly advised to apply for the Invitation Letter at least 4 weeks before foreign scholar’s scheduled arrival, so that they have sufficient time to subsequently apply for his or her visa at a Chinese consulate or embassy in his or her home country or another designated country.