Upon de-registration, the validity of the thoska as a student card is revoked. Although it does not have to be returned, it can no longer be used as a student card after de-registration until re-registration.
After the expiration of the validity you have 4 weeks to settle any remaining credit on your wallet (still at the reduced student prices). After the 4 weeks you can still pay with your card, but then guest prices will be due.
In the event of de-registration at any time during the semester, you must submit the thoska together with your application for de-registration to the Department 1: Studies and Teaching. There the validity imprint will be updated through validation. The same applies to de-registration at the end of the semester, provided that you have already been re-registered for the following semester.