Erasmus students are not obliged to apply for a semester of leave. Nevertheless, it is often used because the semester of leave is counted as a university semester but not as a subject semester and therefore no study time is "lost". You can apply for the leave of absence at the student administration, and you can get a corresponding proof of your study abroad from the Erasmus-- or direct exchange team.

More information about the leave of absence

Reimbursement of semester ticket fees

If you are abroad for at least 3 months or are on leave of absence, you can apply to the AStA semester ticket office for a refund of the fee.