Is it permissible to reserve social housing units through a payment system that includes a reservation down payment and monthly installments with an annual increase, along with a cash subsidy from the Real Estate Financing Fund and bank financing with a diminishing return? If it is not permissible, what are the limits of necessity that would allow it?

It is permissible to purchase an apartment in installments from its owner, even if the deferred price is higher than the immediate price, provided that the total price is mentioned without separating the profit, and that no increase is stipulated in case of delay in payment. If the bank mediates, it must first purchase the property and then sell it to the client in installments. However, if the bank's role is merely financial, by paying the price of the apartment to the owner and recovering it with an increase from the client, then this is a forbidden usurious loan, impermissible except in cases of dire necessity that cannot be averted otherwise.