What is the ruling on dealing with usurious banks that have Islamic windows operating on a partnership basis, where the bank finances the project and obtains profits not exceeding 10% of the capital, and if the realized profits are less than that, the bank refunds the difference, and if the project incurs a loss, the bank bears the full loss?

Muslims must avoid dealing with usurious banks unless absolutely necessary and only through Sharia (definition)-compliant transactions. The Islamic window within a usurious bank does not permit dealings with it unless it is completely independent. The mentioned transaction, where the bank finances a project managed by a partner, and amounts are paid to the bank on account, is permissible. According to the Islamic Fiqh Academy, what is distributed from the project's proceeds before liquidation is considered amounts paid on account. There is no Sharia impediment to the mudarib (managing partner) committing to pay a fixed percentage of the capital to the bank on account of profits, provided there is a subsequent settlement and the bank bears the loss. However, it is forbidden for the Rabb al-mal (financier) to have a fixed amount added to the capital as their share, and it must be a common percentage of the profit. Due to the lack of complete clarity regarding the details of the issue, a definitive ruling cannot be given, and the questioner should clarify the true nature of the transaction.