All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is permissible for you to give the Zakah of your property to your needy brother. But it is insufficient to pay the debt on his behalf from your Zakah, except with his permission, for Zakah should be given to the poor to own, and he then has the choice: to pay his debt if he wishes, or benefit from it in whichever way may be more important, in his sight, than to pay the debt.
Allaah Knows best.