Khums, literally the fifth, is an obligatory religious levy of one fifth, most fully developed in Twelver Shia Islam, where it stands beside zakat as a distinct and major duty. Its scriptural warrant is the Qur'anic verse assigning a fifth of gains to God, the Messenger, his kinsfolk, the orphans, the needy and the wayfarer. Sunni jurisprudence has generally applied this narrowly to the spoils of war and to treasure and mined wealth; Twelver Shia jurisprudence reads it far more broadly, levying the fifth on the annual surplus of a person's income after ordinary living expenses, as well as on mined wealth, treasure, and certain other categories.
This broad application makes khums, in Shia practice, an annual audit of one's net savings comparable in weight to the income obligations of other faiths, and it is a principal means by which the religious establishment is funded independently of the state.