The real estate not offered for sale

Q 2: The inheritors have asked me to request a Fatwa (legal opinion issued by a qualified Muslim scholar) about the real estate that is not being offered for sale by real estate agents or at national newspapers: what is the due Zakah (obligatory charity) on such real state if a buyer comes and offers a reasonable price for them and they are sold? Is Zakah due upon such properties or is it not due until they are sold and the value is received? Must Zakah be paid for all the years in which the properties remained without being sold or just for one year? (Part No. 8; Page No. 128

A: The Zakah is due upon any real estate offered for sale if a Hawl (one lunar year calculated after the property reaches the minimum amount upon which Zakah is due) passes and it is still in the possession of its owner. Its value is to be calculated at the due time of Zakah and 2.5% of the calculated value should be paid, even if it is not offered for sale by real estate agents.