Is the money paid to reduce rent in a mortgage contract, which is refundable upon departure, considered usury (riba)? Is zakat due on it for past years? Is one who remains in this house sinful until a solution is found for the rising rents?

The common mortgage contract in some Maghreb countries is a forbidden usurious contract. The situation of each tenant must be considered individually, based on the extent of their need or necessity to maintain this contract, for necessities permit the prohibited. As for the zakat on this amount, it is obligatory for the tenant because it is his property, and this is according to the most preponderant opinion of the majority of scholars.