According to the Shariah, Fitra becomes incumbent when the new moon of Shawwal is sighted. This is known as Zakat of Fitra, which is Wajib on every Baligh person. If you have a guest with you, who has arrived at your house before sunset on the eve of Eid ul Fitr, then his/her Fitra is Wajib upon you.
As per laws of Ayatollah Seestani's 'Islamic Laws': "At the time of sunset on Eid ul fitr, whoever is adult and sane and is neither unconscious, nor poor, nor the slave of another, he should give, on his own behalf as well as on behalf of all those who are his dependents, about three kilos per head of wheat or barley or dates or raisins or rice or millet etc. It is also sufficient if he pays the price of one of these items in cash."
Therefore, in principle the fitra is on staple food which comes to approximately $10.00 on Basmati rice and $18.00 for dates
Since FITRA becomes wajib when the new moon of SHAWWAL is sighted, Shariah does not recommend advance payment to the Mustahiqqeen. But if you think a particular deserving person or family may benefit better if payment is made to them earlier than Eid-ul-Fitr, you can give away your sum as a loan and then you will make the NIYYAT for that sum being a FITRA, upon the sighting of the new moon.
What is "Fitra"?
Fitra is a gift of food or money that each baligh individual pays on the day of Eid-ul-Fitr, that is, on seeing the new moon of the month of Shawwal. This is a "zakat" or charitable tax.
When should it be paid?
Fitra is only obligatory when the new moon is seen, but, if you think a particular deserving person or family may benefit better if payment is made to them earlier than Eid-ul-Fitr, you can give away your sum as a loan and you make the niyyah (intention) that the sum is your fitra when the new moon is seen.
Who needs to pay it?
It is wajib (obligatory) for every baligh person (one who has reached maturity) to pay fitra. If you have a guest with you, who has arrived at your house before sunset on the eve of Eid-ul-Fitr, then it is obligatory for you to pay their fitra also.
Who will receive the fitra?
If there are those deserving of fitra in your own country, then your fitra should be given locally. Otherwise, see the advice below on whom to give fitra to.
Advice on giving fitra, particularly to local Jamaats:
1. If you come to know of a deserving person or family in your city or country of residence, you will please consider it as a priority case.
2. According to Ayatollah Sheestani the deserving recipient of fitra must be a mumin, Shia Ithna-asheri
3. If a non-Sayyid gives fitra, this can only be given to a non-Sayyid. However the fitra given by a Sayyid can be given to a Sayyid.