Zakaah al-Fitr is often referred to as Sadaqah al-Fitr. The word Fitr means the same as Iftaar, breaking a fast and it comes from the same root word as Futoor which means breakfast. Thus, Islamically, Zakaah al-Fitr is the name given to charity which is distributed at the end of the fast of Ramadan.
Sadaqah al-Fitr is a duty which is Waajib on every Muslim, whether male or female, minor or adult as long as he/she has the means to do so. The proof that this form of charity is compulsory can be found in the Sunnah whereby Ibn `Umar reported that the Prophet (sallallaahu `alaihi wa sallam) made Zakaah al-Fitr compulsory on every slave, freeman, male, female, young and old among the Muslims; one Saa` of dried dates or one Saa` of barely. The head of the household may pay the required amount for the other members. Abu Sa'eed al-Khudree said,
"On behalf of our young and old, free men and slaves, we used to take out during Allah’s Messenger's (sallallaahu 'alaihi wa sallam) lifetime one Saa` of grain, cheese or raisins".
The significant role played by Zakaah in the circulation of wealth within the Islamic society is also played by the Sadaqah al-Fitr. However, in the case of Sadaqah al-Fitr, each individual is required to calculate how much charity is due from himself and his dependents and go into the community in order to find those who deserve such charity. Thus, Sadaqah al-Fitr plays a very important role in the development of the bonds of community. The rich are obliged to come in direct contact with the poor, and the poor are put in contact with the extremely poor. This contact between the various levels of society helps to build real bonds of brotherhood and love within the Islamic community and trains those who have, to be generous to those who do not have.
The main purpose of Zakaah al-Fitr is to provide those who fasted with the means of making up for their errors during the month of fasting. Zakaah al-Fitr also provides the poor with a means with which they can celebrate the festival of breaking the fast (`Eid al-Fitr) along with the rest of the Muslims. Ibn Abbaas reported,
"The Prophet (sallallaahu 'alaihi wa sallam) made Zakaah al-Fitr compulsory so that those who fasted may be purified of their idle deeds and shameful talk (committed during Ramadan) and so that the poor may be fed. Whoever gives it before Salaah (before Eid al Fitr prayer) will have it accepted as Zakaah, while he who gives it after the Salaah has given Sadaqah." Hence, the goal of Sadaqah al-Fitr is the spiritual development of the Believers. By making them give up some of their wealth, the believers are taught the higher moral characteristics of generosity, compassion (sympathy for the unfortunate), gratitude to God and the righteousness. But, since Islam does not neglect man's material need, part of the goal of Zakaah al-Fitr is the economic well-being of the poorer members of society.
Zakaah al-Fitr is only Waajib for a particular period of time. If one misses the time period without a good reason, he has sinned and can not make it up. This form of charity becomes obligatory from sunset on the last day of fasting and remains obligatory until the beginning of Salaah al-'Eid' (i.e. shortly after sunrise on the following day). However, it can be paid prior to the above mentioned period, as many of the Sahaabah [companions of the Prophet (sallallaahu 'alaihi wa sallam)] used to pay Sadaqah al-Fitr a couple days before the `Eid. Naafi reported that the Prophet's companion Ibn `Umar used to give it to those who would accept it and the people used to give it a day or two before the `Eid. Ibn `Umar reported that the Prophet (sallallaahu 'alaihi wa sallam) order that it (Zakaah al-Fitr) be given before people go to make the Salaah (al-'Eid).
And Ibn `Abbaas reported that the Prophet (sallallaahu 'alaihi wa sallam) said, "Whoever gives it before the Salaah will have it accepted as Zakaah, while he who gives it after the Salaah (will not, for it will only be considered as) ordinary charity. Therefore, one who forgets to pay this Zakaah al-Fitr on time should do so as soon as possible even though it will not be counted as Zakaah al-Fitr.
The amount of Zakaah is the same for everyone regardless of their different income brackets. The minimum amount is one Saa` (two handfuls ) of food, grain or dried fruit for each member of the family.
This calculation is based on Ibn `Umar's report that the Prophet(sallallaahu 'alaihi wa sallam) made Zakaah al-Fitr compulsory and payable by a Saa` of dried dates or a Saa` of barley. The Sahaabee, Abu Sa`eed al-Khudree said, "In the Prophet's time, we used to give it (Zakaah al-Fitr) as a Saa` of food, dried dates, barley, raisins or dried cheese".
 Collected by Bukhaari - Arabic/English, vol. 2, p. 339, no. 579
 Collected by Muslim - English transl. vol. 2, p. 469, no. 2155
 Collected by Abu Dawood - Eng. transl. vol. 2, p. 421, no. 1605 - rated Sahih by Shaikh Naser Al-Albaani
 Collected by al-Bukhaari - Arabic/English, Vol. 2, p.339, no. 579
 Collected by al-Bukhaari - Arabic/English vol. 2, p. 340, no. 582