The main purpose of Zakat ul-Fitr is to provide the poor which they can celebrate the festival of breaking the fast (Eid ul-Fitr) along with the rest of the Muslims.
Every Muslim is required to pay Zakat ul-Fitr at the conclusion of the month of Ramadan as a token of thankfulness to God for having enabled him or her to observe the obligatory fast. Its purpose is:
As a levy on the fasting person. This is based on the Hadith: The Prophet of Allah said, "The fasting of the month of fasting will be hanging between earth and heavens and it will not be raised up to the Divine Presence without paying the Zakat ul-Fitr."
To purify those who fast from any indecent act or speech and to help the poor and needy.
The latter view is based upon the hadith from Ibn `Abbas who related, “The Prophet of Allah enjoined Zakat ul-Fitr on those who fast to shield them from any indecent act or speech and for the purpose of providing food for the needy. It is accepted as Zakat for the one who pays it before the `Eid prayer