✅ Answer: Please pay attention to the following narrations:

1 عن أَبِي عبداللَّه قال صَدَقَةُ الْفِطْرَةِ عَلَى كُلِّ رَأْسٍ مِنْ أَهْلِكَ الصَّغِيرِ وَ الْكَبِيرِ وَ الْحُرِّ وَ الْمَمْلُوكِ وَ الْغَنِيِّ وَ الْفَقِيرِ.... لِفُقَرَاءِ الْمُسْلِمِين

📚 Tahdhib Vol. 4, p. 75

Imam Sadiq (peace be upon him) said: 'Zakat al-Fitr is for every person, young and old, free and enslaved, poor and rich, in your household,' until he said: 'for the poor Muslims!'

2 عَنْ مُعَاوِيَةَ بْنِ عَمَّارٍ عَنْ أَبِي عَبْدِ اللَّهِ فِي الْمَوْلُودِ يُولَدُ لَيْلَةَ الْفِطْرِ وَ الْيَهُودِيِّ وَ النَّصْرَانِيِّ يُسْلِمُ لَيْلَةَ الْفِطْرِ قَالَ لَيْسَ عَلَيْهِمْ فِطْرَةٌ لَيْسَ الْفِطْرَةُ إِلَّا عَلَى مَنْ أَدْرَكَ الشَّهْرَ.

📚 Al-Faqih Vol. 2, p. 179

Imam Sadiq (peace be upon him) said about a child born on the night of Eid al-Fitr and a Jew or Christian who becomes a Muslim on the night of Eid al-Fitr: 'There is no Zakat al-Fitr for them. Zakat al-Fitr is only for those who have experienced the month of Ramadan!'

✅ Based on the above narrations and others, even though Zakat al-Fitr is an obligation for all the dependents of a man, whether young or old, free or enslaved, male or female, if a child is born on the night of Eid al-Fitr, meaning after the sunset of the last day of Ramadan, there is no Zakat al-Fitr for him and there is no need to pay Zakat al-Fitr for him.

Also, if a Jewish or Christian person becomes a Muslim on the night of Eid al-Fitr, there is no Zakat al-Fitr on him for that year, unless he is the slave of a Muslim, in which case his master pays his zakat:

3 عَنْ مُحَمَّدِ بْنِ يَحْيَى عَنْ مُحَمَّدِ بْنِ أَحْمَدَ رَفَعَهُ عَنْ أَبِي عَبْدِ اللَّهِ قَالَ: يُؤَدِّي الرَّجُلُ زَكَاةَ الْفِطْرَةِ عَنْ مُكَاتَبِهِ وَ رَقِيقِ امْرَأَتِهِ وَ عَبْدِهِ النَّصْرَانِيِّ وَ الْمَجُوسِيِّ وَ مَا أَغْلَقَ عَلَيْهِ بَابَهُ.

📚 Al-Kafi Vol. 4, p. 174

Imam Sadiq (peace be upon him) said: 'A man pays Zakat al-Fitr for his mukatab (a slave who works with the permission of his owner to pay for his freedom) and his wife's slave, and his Christian and Zoroastrian servant, and the one on whom he closes the door of his house (i.e., all his dependents)!'

✅ So, Zakat al-Fitr is only required for a person who has reached the month of Ramadan, but the amount of his age makes no difference. Therefore, sometimes a child who is one day old is subject to Zakat al-Fitr.

اللَّهُمَّ فَصَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ