Sadaqat-ul-fitr is an obligation for every Muslim, male or female, who owns 613.35 grams of silver or its equivalent, either in the form of money, ornaments, stock-in-trade or in the form of some goods or commodities beyond one's normal needs. Every person who owns such an amount has to pay Sadaqat-ul-fitr, not only on behalf of himself but also on behalf of his minor children. The prescribed amount of Sadaqat-ul-fitr is 1.75 kilograms of wheat or its value in money. This amount is prescribed for paying Sadaqat-ul-fitr for one person only. If a person has some minor children, the same amount has to be paid on behalf of each one of them separately. The following points must be remembered with regard to the payment of Sadaqat-ul-fitr.
1. Sadaqat-ul-fitr is obligated on each adult male or female separately, and the relevant adult person himself is responsible to pay it. The husband is not required to pay Sadaqat-ul-fitr on behalf of his wife nor is the wife supposed to pay it on behalf of her husband. Similarly, a father is not bound to pay Sadaqat-ul-fitr on behalf of his adult children or vice versa. However, if the head of the family, by his own free will, wishes to pay Sadaqat -ul-fitr for each one of the members of his family, he should seek their authorisation for that purpose. In this case the Sadaqat-ul-fitr paid by him will be valid on their behalf. If he did not pay Sadaqat-ul-fitr on behalf of his family, he will not be responsible for it. Rather, it is the duty of every adult member of the family to discharge his own obligation or request the head of the family to pay it on his or her behalf.
2. It is a Sunnah that the Sadaqat-ul-fitr is paid before performing the ‘Eid prayer. It can also be paid before the ‘Eid day, but it is not advisable to delay it up to the performance of ‘Eid prayer. However, if a person has failed to pay on its proper time, he should pay it as soon as possible, whereupon the obligation will stand discharged.
3. The Sadaqat-ul-fitr is not necessary on behalf of a child who has been born after the break of dawn in the ‘Eid day, nor is it necessary to pay Sadaqat-ul-fitr on behalf of person who dies before the dawn of the ‘Eid day.
4. Sadaqat-ul-fitr should only be paid to a person who is entitled to receive Zakah.
It is according to Imam Abu Haneefah ruling on minor details
source with thanks: Darul Uloom Bury, United Kingdom http://www.inter-islam.org/