All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
You are not obliged to pay Zakat for the advance rent which you received until a complete lunar year elapses on it.
For more benefit on Zakat on rented properties, the conditions on paying Zakat on them and the amount of Zakat, please refer to Fatwa 85524.
Allaah Knows best.