Zakaat of unlawful earnings
The wealth/money of which Zakaat is being given should have been earned through permissible lawful means. The wealth gained through unlawful means is actually vile wealth. The ruling as per the Shariah is that it will be returned to its respective owner. If the owner can’t be traced or returning to the owner is really difficult, then in the light of the Shariah, it has to be given away in charity. As mentioned in Radd Ul Muhtaar, Kitaab Uz Zakaat.
The person earning unlawful earnings is committing a grievous sin and deserves grave punishment. Such a person should repent wholeheartedly before Allah Most High and should be regretful of his/her actions in this regards and should make a firm resolve of not repeating such actions again.
Among the conditions for Zakaat is that the person should be the absolute owner of wealth which meets the prescribed criterion of Zakaat. As wealth gained through unlawful means is not the wealth of that person at all, how can Zakaat be compulsory on such a person? Such a person in fact must return the unlawfully gained wealth to the owner. If this is not possible, then all the unlawful earnings have to be given away in charity.
May Allah guide all of us to obey Him and His Prophet (Sallallahu alaihi wa sallam) in all walks of life and may He accept our obedience.