The regular deadline is 30 April.
Late applications are accepted as followes (CHF 150.00 charge for late applications):
until 31.08.: For applicants who do not require a visa (citizens of CH, EU, EFTA, Japan, New Zealand)
until 30.06.: For applicants who require a visa (citizens of all other countries)
If you are not sure whether you require a visa, please check the website of the State Secretariat for Migration (SEM): https://www.sem.admin.ch/sem/en/home/publiservice/weisungen-kreisschreiben/visa/liste1_staatsangehoerigkeit.html
Please note that application fees can neither be reimbursed nor transferred to another semester.