According to the Fatwas of Grand Ayatollah Sistani, to whom Should zakat al-fitr be given?
what follows is the answer of the above question:
Ruling 1. Based on obligatory precaution, zakāt al-fiṭrah must only be given to the poor, and this means poor Shias who satisfy the criteria mentioned previously regarding those who are entitled to receive zakat. In the event that there are no poor Shias in one’s town, he can give it to other Muslims who are poor, but in any case, fiṭrah must not be given to a nāṣibī.
Ruling 2. If a Shia child is poor, one can spend fiṭrah on him or make it his property by entrusting it to his guardian.
Ruling 3. It is not necessary that the poor person to whom fiṭrah is given be a just person (ʿādil); however, the obligatory precaution is that fiṭrah must not be given to someone who consumes alcohol, or does not perform prayers, or publicly commits sins.
Ruling 4. Fiṭrah must not be given to someone who spends it for sinful purposes.
Ruling 5. The recommended precaution is that a poor person should not be given fiṭrah that is less than one ṣāʿ unless the total amount of fiṭrah is not sufficient for all the poor people. However, there is no problem if more than one ṣāʿ is given.
Ruling 6. If a person gives half a ṣāʿ of an item on account of it being double the price – for example, if a particular type of wheat is double the price of ordinary wheat and one gives only half a ṣāʿ – it is not sufficient. In fact, even if he gives it with the intention of paying the value of the fiṭrah, it is not sufficient.
Ruling 7. A person cannot give as fiṭrah half a ṣāʿ of one item, such as wheat, and half a ṣāʿ of another item, such as barley. In fact, even if he gives it with the intention of paying the value of the fiṭrah, it is not sufficient.
Ruling 8. It is recommended that in giving zakāt al-fiṭrah one should prefer his poor relatives and neighbours over others, and it is befitting that he also gives preference to learned, religious, and virtuous persons over others.
Ruling 9. If a person gives fiṭrah to someone thinking that he is poor but later realises that he was not poor, in the event that the item he gave him has not perished, he must take it back and give it to someone who is entitled to receive it; and if he is unable to take it back, he must replace the fiṭrah from his own property. If the item has perished, in the event that the beneficiary knew the item was given as fiṭrah, the beneficiary must replace it; however, if the beneficiary did not know, then replacing it is not obligatory on him and the benefactor must replace it.
Ruling 10. A person cannot give fiṭrah to someone who says he is poor unless he is confident that what he says is the truth or he knows that he was poor previously.
source:sistani.org