All perfect praise be to Allah, The Lord of The Worlds, and may His blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
We would like to attract your attention to the fact that we have already clarified the ruling of Sharia on Zakatulfitr in Resolution No.(6/2022) issued by the Board of Iftaa`, Research and Islamic Studies, pointing out that it is an obligatory charity. Moreover, when a Muslim delays paying it, although he is aware of its due time, he incurs a sin, and he must make repentance and pay it. This is because Zakatulfitr is an act of worship that a Muslim remains liable for, even if its time has expired, just like prayer; however, his fasting is considered valid. Moreover, giving Zakatulfitr starts from the beginning of Ramadan and ends with the sunset of the first day of Eidulfitr, according to the consensus of the Muslim scholars.
Ashirazi, (may Allah have mercy on him) said: "It is preferable to pay it before going out for the Eid prayer because Ibn 'Umar reported that the Messenger of Allah (PBUH) ordered that the Sadaqat-ul-Fitr should be paid before the people go out for prayer." {Agreed upon} In addition, it isn`t permissible to pay it after the first day of Eid because the Prophet (PBUH) said: "Save them (i.e. the poor) wondering around (in the markets and the streets asking for food) on that day.” {Narrated by al-Baihaqi}. Therefore, if he didn`t pay it on the first day of Eid, then he has incurred a sin, and he must pay it because it is a financial obligation that he has failed to deliver, and he isn`t considered free from the liability just because its payment time has expired."
Moreover, An-Nawawi (may Allah have mercy on him) said: "Shafii texts and those of the fellow scholars have agreed that it is better to pay Zakatulfitr before going out for Eid prayer.
Still, it is permissible to pay it at any time of that day.
In addition, it is impermissible to delay its payment till after the day of Eid, and one who does so is considered sinful, and it remains a debt that he is obliged to pay off. These scholars have called paying it after the day of Eid as "make up for Zakatulfitr". {Al-Majmou`vol.6/pp.84}. And Allah Knows Best.