Is it permissible to purchase an apartment on a contributory installment plan, where the first installment is paid before construction, and subsequent installments are collected according to the three construction phases, with the state contributing 30% of the amount?

Purchasing apartments falls under the contract of Istisna' (manufacturing contract), which has been approved by the Islamic Fiqh Academy with two conditions: specifying the type, kind, quantity, and required characteristics of the manufactured item, and defining the deadline. In this contract, it is permissible to defer the entire price or pay it in installments. It is also permissible to include a penalty clause unless there are unforeseen circumstances. Therefore, if the apartment is purchased with a description that removes ambiguity and is free from other Sharia-prohibited elements, then it is permissible.