Is it acceptable for him to put his money with his wife’s money and pay zakaah together?
Question

                I am employed and my wife is too, and my money and hers are one – we take from both. The way in which we pay zakaah on our wealth is that I work out how much money we have altogether on the specified date in Ramadaan in addition to the gold, then I divide the total by forty. Is there anything wrong with combining the wealth and the way in which I pay zakaah?.
Praise be to Allah.
    There is nothing wrong with combining your money with your 
    wife’s money and gold, then paying zakaah on the total. That is because the 
    zakaah on money, gold and silver does not change, whether it is combined or 
    dealt with separately, because what matters is paying one-quarter of 
    one-tenth, whether there is a little wealth or a lot, so long as it has 
    reached the nisaab.  

    Combining or separating wealth only makes a difference to 
    zakaah in the case of an’aam animals (camels, cattle and sheep). 

    What you and your wife are doing with your salaries and 
    paying zakaah on them and on the gold that she has in one month is best and 
    is the easiest way of paying zakaah on one's salary. 

    What you have done by dividing your wealth by forty is also 
    correct, because the rate of zakaah to be paid on gold and cash is 
    one-quarter of one-tenth which is one in forty.  

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on him) 
    was asked: 

    There is a man who depends on his monthly salary; he spends 
    some and saves the rest. How should he pay zakaah on this money? 

    He replied: 

    He should write down what he saves of his salary, and pay 
    zakaah on it when one year has passed.  Zakaah should be paid on the savings 
    of each month when one year has passed. If he pays zakaah on the total in 
    the first month, there is nothing wrong with that and he will be rewarded 
    for that, and it will be regarded as zakaah paid in advance for the savings 
    for which one year has not yet passed. There is no reason why a person 
    should not pay zakaah in advance if he sees some benefit in doing so. But 
    delaying it after the year has passed is not permissible, unless there is a 
    valid shar’i excuse, such as the wealth not being available or there being 
    no poor people. End quote. 

    Tuhfat al-Ikhwaan bi Ajwabah Muhimmah tata’allaq bi Arkaan 
    al-Islam (question no. 12) 

    For a detailed discussion about zakaah on one’s salary, 
    please see question no. 26113, in 
    which we quote a fatwa from the Standing Committee that is similar to the 
    fatwa from Shaykh Ibn Baaz (may Allaah have mercy on him). 

    And Allaah knows best.