Khums (One-fifth Levy or Tax Income)
Setting aside one-fifth of the amount of a year's savings, (after deducting all the lawful expenses from the earnings of that year) is called Khums.
The descendants of the Holy Prophet (Sadaat), provided they are Ithna ‘Ashari (followers of the 12 Imams) and poor, will get half of the Khums, while the other half belongs to Imam (A.S.) of the time. During the occultation (ghaybah) of the Imam (A.S.), his share should be handed over to the presiding Mujtahid.
The Quranic command for this is as follows:
“And know that out of all wealth that you may acquire, one-fifth of it is for Allah, and for the Messenger and for his kinsmen, and the orphans, the poor and the wayfarer”. (8:41)