Zakatul-Fitr is one Sa` (2 kilos, 40 gms) of food that a man offers at the end of Ramadan. Its reason is showing gratitude to Allah for His Favors by completing the month of Ramadan. When the sun of the last day sets, it becomes obligatory to pay it. Zakatul-Fitr is an obligatory duty which the Messenger of Allah (peace be upon him) ordained as `Abdullah ibn `Umar (may Allah be pleased with him) narrated: “Allah ’s Messenger (peace be upon him) made it obligatory to pay sadaqat-ul-Fitr of Ramadan at a Sa` of dates or barley on every freeman or slave, male or female of the Muslims.” [Reported by Al Bukhari and Muslim].
Ibn `Abbas said: “The Messenger of Allah (peace be upon him) prescribed the sadaqah (alms) relating to the breaking of the fast as a purification of the fasting from empty and obscene talk and as food for the poor.” [Reported by Abu Dawud, Ibn Majah, and Al Hakim who graded it as authentic].
It is obligatory on every Muslim whether a male or female, young or old. It is desirable to pay it on behalf of embryo.
As for the time of paying it, it has two times: A virtuous time and permissible time. As for the virtuous time, it is the morning of the `Eid day before Salah due to the Hadith of Sa`id Al Khudry (may Allah be pleased with him) who narrated: “In the life-time of Allah’s Messenger (peace be upon him), we used to give one Sa ‘ of food (edible things) as Sadaqat-ul-Fitr (to the poor).” [Reported by Al Bukhari and Muslim]
As for the time of permissibility, it is one or two days before `Eid due to the Hadith of Nafi` who reported that Ibn `Umar used to give Sadaqat-ul-Fitr for every young and old person. He even used to give on behalf of my children. Ibn ‘Umar used to give Sadaqat-ul-Fitr to those who had been officially appointed for its collection. People used to give Sadaqat-ul-Fitr (even) a day or two before the `Eid. It is not permissible to delay it after the `Eid Salah. So, if a person delays it after the `Eid Salah without an acceptable cause, it shall not be accepted because he has disagreed the action of the Prophet (peace be upon him).