Is it permissible to pay zakaah in advance on every sum of money he saves?
Question

                There is someone who receives a monthly salary; he spends some of it on his needs and puts a small amount aside to save it. Can he pay zakaah on that part that he saves and regard it as zakaah paid in advance?.
Praise be to Allah.
      Firstly: 

    The way in which zakaah is to be paid on monthly salaries has 
    been described previously, in the answer to question no.
    26113. 

    Secondly: 

    If a Muslim wants to pay zakaah in advance for every sum of 
    money he sets aside, there is nothing wrong with that, so long as he owns 
    the nisaab (minimum threshold), because paying zakaah in advance before 
    being in possession of the minimum threshold is invalid. 

    Ibn Qudaamah (may Allah have mercy on him) said: It is not 
    permissible to pay zakaah in advance before being in possession of the 
    minimum threshold, and there is no difference of scholarly opinion on that 
    as far as we know.  

    If he has part of the minimum threshold in his possession and 
    pays zakaah in advance, or pays zakaah as if he had the minimum threshold, 
    that is not permissible, because that is hastening to carry out the ruling 
    before its cause is present. End quote from al-Mughni (2/260). 

    It says in al-Fataawa al-Hindiyyah: It is permissible 
    to pay zakaah after taking possession of the minimum threshold, but it is 
    not permissible to do so before that. End quote. 

    It says in al-Maswoo‘ah al-Fiqhiyyah (23/294): 

    The majority of fuqaha’ - including the Hanafis, Shaafa‘is 
    and Hanbalis, and Abu ‘Ubayd and Ishaaq, are of the view that it is 
    permissible for the individual to hasten to pay the zakaah of his wealth 
    before it is due. 

    But for that to be permissible, they stipulated that the 
    nisaab (minimum threshold) must be present; it is not permissible to pay 
    zakaah in advance before the minimum threshold is there, and there is no 
    difference of opinion concerning this matter. End quote. 

    And Allah knows best.