The payment period varies between 9 and 12 months, i.e. the number of months of the year for which the rent is to be paid.
For apartments, the payment period is 12 months, whereas the payment period for corridor rooms is 9 months. A 9-month rent means that during the summer months (June, July and August) no rent is debited. Students who live in a corridor room only pay rent from September to May, even though they live there for the full year.
Exception! If the tenancy relationship begins during the summer months, rent has to be paid for the move-in month.