Is it permissible to purchase a house in installments from the Housing Authority in Turkey, given that the installment amount is increased annually based on the inflation rate, while the number of installments remains fixed, making the final amount paid undefined?

It is permissible to sell on credit or by installments with an increase in price compared to a spot sale. If the sale is completed, the remaining amount becomes a debt owed by the buyer. It is not permissible to increase this debt for any reason, such as inflation or delay in payment, because such an increase is usury (riba). The resolution of the Fiqh Academy stipulated the prohibition of any increase on a debt in case of delayed payment, as well as forbidding penalty clauses in contracts where the primary obligation is a debt. Based on this, the increase imposed by thekan Housing Authority on the remaining amount, in consideration of inflation, is considered forbidden usury (riba), and it is not permissible to deal with it in this situation.