What is the time for giving out zakat, and must it be given out in Muharram or is it permissible in Rabi' al-Thani? Who are the recipients of zakat, and is it permissible to give it to brothers or to a divorced sister experiencing difficult financial circumstances?

Zakat (definition) is obligatory for whoever owns the nisab (definition) and a full lunar year has passed over it. It does not have a specific time like Muharram. The eligible recipients of Zakat are: the poor, the needy, those employed to collect it, those whose hearts are to be reconciled, those in bondage, the indebted, in the cause of Allah, and the wayfarer, as stated in verse 60 of Surat At-Tawbah (definition). It is permissible to give Zakat to poor siblings, and to a sister whose husband refrains from spending on her and who does not have wealthy children, provided that it is not possible to compel her husband to provide the obligatory maintenance, and that she is not disobedient (nashiz) and capable of securing her own maintenance.