In the integrated curricula of Medicine, students must complete 100% of the required courses. In other curricula, you must check for 1) minimal fulfilment of curriculum; 2) required fulfilment volume; 3) free curriculum volume. The minimal fulfillment criterion is only applicable to freshmen who have to complete 15 ECTS (1 ECTS = 26 hours) in their first semester – otherwise they will be deleted from the matriculation register. You can study full- and part-time at the university, in the first case, you have to complete 75%-100% of the curriculum each semester. Since the regular volume of studies per semester is 30 ECTS, you have to complete at least 45 ECTS by the end of the first year, 90 ECTS at the end of the second and 135 ECTS at the end of the third year. If the requirements are not met, the student will be registered as a part-time learner. In order to not pay tuition fees, you have to complete 30 ECTS per semester, the buffer is 6 ECTS (cumulative calculation, i.e. 24 ECTS in the first semester, 54 in the second, etc.). Note that only courses in your curriculum count! If you´ve completed a sufficient amount of optional courses, they will not count towards fulfilment of the curriculum. Since the system is cumulative, additional credits passed in one semester will count towards the fulfilment requirements of the next semester and you can allow yourself some rest. More info here.