Is it permissible for a man to pay the Zakat on his wealth to his daughter's husband, who is a salaried employee with a low income and whose children are studying in foreign universities?

It is permissible to give zakat to the daughter's husband if he is deserving of it, due to the generality of Allah's statement: (Zakat expenditures are only for the poor and for the needy...) [At-Tawbah/60]. The poor and the needy are those who do not find enough money for their sustenance, or whose income is not sufficient to cover their basic needs and their family's expenses for a year. He should be given what suffices his needs. A person's expenditures must be balanced with his income; he should not spend vast amounts of money on dispensable matters and then ask people for help.