The World Federation One Stop Fiqh

Ruling 1878

It is a condition for zakat to be liable on things other than wheat, barley, dates, and raisins, that the owner be able to have disposal over them legally and actually. Therefore, if for a significant period during the year someone usurps them [and so he cannot actually have disposal over them], or if the owner is legally forbidden to have disposal over them, then there is no zakat to pay.