Is it permissible to give zakat to a poor brother who supports eight children, owns a piece of land, and owes money to the questioner? And is he required to sell the land? Is it permissible to give zakat to a poor sister for medical treatment or other expenses, in addition to my own assistance to her? What are the essential needs that define poverty and destitution? And do these differ according to the customs and living standards of society?

If your brother is in debt, has children, and his salary is insufficient to cover his essential needs, then it is permissible to give him from Zakat. In fact, it is better, as it combines charity and kinship. He is not obligated to sell his land. As for the mother, brother, and sister, if they do not find enough to cover their essential needs, it is permissible to give them from Zakat. However, it is not permissible to give Zakat to someone whose financial support is obligatory upon you, such as the mother, by scholarly consensus, and likewise the brother and sister according to some scholars. The poor person eligible for Zakat is one who does not find enough to cover his essential needs and those of his dependents. The estimation of this is based on the local custom. Medical treatment is considered among essential needs, and it is permissible to give Zakat for study expenses in certain cases.