What is the ruling on a salary from working in a housing rental institution that leases property for a monthly sum, increases the rent if payment is delayed, deals with usurious banks, and where the employee registers tenant files?

Stipulating an increase upon late payment is considered usury (riba). If the debtor is solvent, he is compelled to pay. If he is insolvent, he should be given respite until he becomes solvent, or charity should be given to him, as Allah Almighty says: "And if there is one in [financial] hardship, then [let there be] postponement until [a time of] ease. But if you remit [it by way of charity], that is better for you, if you only knew."

As for working in an institution that deals with usury, it is not permissible if all its work is prohibited. However, if some of its work is permissible, then it is permissible to work in the permissible section, provided that it has no connection to usury. Nevertheless, it is better and safer to avoid such institutions altogether.