1. The Spoils
It is the moveable property seized in a battle from the non-Muslims with whom fighting is lawful. Twenty percent of such property belongs to the Imam (a.s.), provided, the fight took place with his permission or his representative such as a Qualified Mujtahid. The same rule applies even if his permission was not given and the fighting had been in the form of an attack to call and an invitation to Islam or a defensive move.
Rule 1. Whatever is taken from such people, without fighting, in the form of Islamically illegal interest or false claims will not be subject to Khums according to the rules of spoils. They will simply be dealt with according to the rules of net savings by usual earnings, (perhaps under the rules of the property of unknown owner).
Rule 2 According to authentic sources a standard quantity is not a condition in the case of spoils. Spoils must not be usurped from a Muslim or those whose property is protected by the Islamic Laws. The usurped spoils must be returned to the owner. If one has obtained the property of hostile non-Muslims by usurpation or has been entrusted with it etc., it will be considered as if it is his own property.
Rule 3. The property obtained from the people bitterly hostile to the qualified successors of the Prophet (the Imam a.s.), according to a necessary precaution, will also be taxable, and will be dealt with by the rules applicable to spoils.