What do the rich
    have to do after paying Zakaah?
Question

                If someone is extremely wealthy how much
      of their wealth should they keep for themselves? Are they allowed to buy a big house or
      should they give more money to the poor?
Praise be to Allah.What is obligatory on the wealth of the rich is zakaah;
    whatever is left after paying zakaah, even if it is a lot, is halaal (permissible) for
    them and it is permissible for them to buy a big house, but they should avoid extravagance
    because it is haraam in Islam even if the extravagant person is rich, because Allaah says
    (interpretation of the meaning):
“… and waste not by extravagance. Verily, He likes not
    those who waste by extravagance.” [al-An’aam 6:141]
It is mustahabb for them to give charity to the poor apart from zakaah,
    and the best charity is that which comes from richness. According to Islam, they are also
    obliged to honour their guests and help those who are in desperate need, and to give to
    poor people who ask for help – even if they have already paid their zakaah. And
    Allaah knows best.