1. As an obligatory precaution Fitrah should be paid to Shiah poor only, who fulfil the conditions mentioned for those who deserve receiving Zakat. But if there is no deserving Shiah in one's hometown, it can be given to other deserving Muslims. But in no circumstances should Fitrah be given to Nasibi - the enemies of Ahlul Bait (A.S)
2. If a Shiah child is poor, one can spend fitrah on him, or make it his property by entrusting it to its guardian.
3. It is not necessary that the poor to whom fitrah is given should be Adil (a just person). But, as an obligatory precaution, fitrah must not be given to a drunkard, or one who does not offer his daily prayers, or commits sins openly.
4. Fitrah should not be given to a person who spends it on sinful acts.
5. The recommended precaution is that a poor person should not be given fitrah which is less than a sa'a (about 3 kilos). However, there is no harm if more than that is given to him.
6. When the price of a superior quality of a commodity is double that of the ordinary, like, when the price of a particular kind of wheat is double that of the price of its ordinary kind, it is not sufficient to give half a sa'a of the wheat of superior quality as fitrah. Also, it is not sufficient if the value of half a sa'a is given with the Niyyat of fitrah.
7. One cannot give as fitrah, half a sa'a of one commodity (eg. wheat) and half a sa'a of another commodity (eg. barley), and if he gives these with the Niyyat of paying the price of fitrah even then it is not sufficient.
8. It is Mustahab that while giving Zakat of fitrah, one should give preference to one's poor relatives and neighbours, and it is good to give preference to the learned persons over others.
9. If a man gives fitrah to a person thinking that he is poor, and understands later that he was not poor, so if the property which he gave to him has not ceased to exist, he should take it back from him, and give it to a person who deserves. But if he cannot take it back from him, he should replace it from his own property. And if what he gave as fitrah is used up, and the person who took fitrah knew that he had received fitrah, he should gives its substitute, but if he did not know it, it is not obligatory on him to give substitute, and the man who gave fitrah should give it once again.
10. If a person claims to be poor, fitrah cannot be given to him unless one is satisfied with his claim; or, if one knows that the claimant has been poor previously.
Miscellaneous matters regarding Fitrah
1. One should give fitrah with the Niyyat of Qurbat, that is, to fulfil the orders of Almighty Allah, and should do niyyat of giving the fitra.
2. It is not correct to give fitrah before the month of Ramadhan, and it is better that it should not be given even during the month of Ramadhan. However, if a person gives loan to a poor person before Ramadhan, and adjusts the loan against fitrah, when payment of fitrah becomes obligatory, there is no harm in it.
3. It is necessary that wheat or any other thing which a person gives as fitrah is not mixed with another commodity or dust, and if it is mixed, but in its pure form it equals a sa'a (about 3 kilos) and the quantity of the thing mixed with it is negligible or usable, there is no harm in it.
4. If a person gives fitrah from a thing which is inferior or defective, it will not be sufficient.
5. If a person gives fitrah on behalf of a number of persons, it is not necessary for him to pay all from the same commodity. For example, if he gives wheat as fitrah of some of them and barley for others, it is sufficient.
6. If a person offers Eid ul fitr prayers, he should, on the basis of obligatory precaution, give fitrah before Eid prayers. But if he does not offer Eid prayers, he can delay giving fitrah till Zuhr.
7. If a person sets aside fitrah from his main wealth, and does not give it to a person entitled to receive it till Zuhr of Eid day, he should make Niyyat of fitrah when he gives it.
8. If a person does not give fitrah at the time when its payment becomes obligatory, and does not also set it aside, he should give fitrah later on the basis of precaution, without making the Niyyat of Ada or Qadha.
9. If a person sets aside fitrah, he cannot take it for his own use, and replace it with another sum or thing.
10. If a person possesses wealth whose value is more than fitrah, and if he does not give fitrah but makes a Niyyat that a part of that wealth is for fitrah, according to obligatory precaution it is not accepted.
11. If the thing set aside for fitrah is lost, he should replace it if a poor person was available, and the fitrah giver delayed giving it, or, he failed to look after it properly. But, if a poor person was not available, and he cared for it properly, he is not responsible to replace it.
12. If a deserving person is available in the hometown of a person, the obligatory precaution is that he should not transfer the fitrah to some other place, and if he does and it is lost, he should give its replacement.
These laws are according to Aayatullah Sistani's Fataawa.