Is it permissible for a son to pay Zakat from his wealth to his poor father who does not possess what he can spend on his household?

There is no harm in giving zakat to a poor stepfather, according to the majority of scholars, because his maintenance is not obligatory upon his wealthy stepson. However, it is preferable to give him voluntary charity. If the mother is poor and her husband is also poor, then her maintenance becomes obligatory upon her son.