Zakat-al-Fitr is specifically related to the month of fasting and is given before the special Eid prayer. The reason for this Zakat is two-fold. According to a Hadith reported by Ibn 'Abbas: The Prophet made Zakat al-Fitr obligatory for the fasting person to keep him from idle talk and indecent conversation and to provide food for the needy. Discharging the duty before the prayer is an accepted Zakat while discharging it after the prayer is just sadaqah (voluntary charity).
In its external form then, Zakat is an annual tax. But, in essence it is the principle on which God and his creatures have a right to a share in one’s property.
Zakat-al-Fitr perfects the fast of Ramazan and purifies the fast of any indecent act or speech. It is obligatory on all Muslims: young, old, male and female. Every Muslim who possesses over and above what is needed as basic food for the duration of one day and night must pay Zakat-al-Fitr for himself and his dependents and distribute it amongst the poor and needy. The earlier it is given the easier it is for them to make arrangements, so that they may also take part in the celebrations of Eid without any difficulties.
Source: Spirit of Islam July 2014