Becoming a Muslim or Becoming Baaligh in Ramadhaan During the Day

1. If a person became a Muslim in Ramadhaan during the day, then he/she cannot eat or drink anything for the rest of the day.
2. Similarly, if a boy or girl became baaligh in any day of Ramadhaan, then it is not permissible for them to eat for the rest of the day.
3. In the two cases mentioned, if the person did eat something, there is no Qadha.

(Behshti Zewar)