If a person mixes his halal wealth with haram money, zakat will have to be given on the total amount.
If a person passes away without paying the zakat which was wajib on him, zakat will not be taken from his wealth. But if he makes a bequest that his zakat must be paid from his wealth, then this zakat will be taken from one third of his wealth irrespective of whether this one third will be sufficient for the payment of his zakat or not. If his inheritors agree to give from the balance of his wealth (i.e. more than the one third), it will be permissible to take from this balance according to the amount that the inheritors specify.
If the creditor forgives his debtor from paying his debt after the expiry of one year, the creditor will not have to pay zakat on this money for that year. However, if the debtor is a rich person, the creditor’s forgiving him will be regarded as if he is destroying his wealth. The creditor will therefore have to give zakat on this wealth. This is because the destroying of zakatable wealth does not absolve one from paying zakat.
The giving of optional charities is only mustahab when one’s wealth is over and above one’s necessities and the necessities of one’s family members. If it is not so, it will be makruh to give optional charities. Similarly, it is also makruh to give all one’s wealth to charity. However, if the person has fullconviction on his trust in Allah Ta’ala and on his ability to exercise patience and there is no possibility of any harm befalling his family, it will not be makruh to do so. Instead, it will be better to give all his wealth in charity.