What is the ruling on intentionally ejaculating during the daytime in Ramadan, and what are the consequences of that, such as making up the fast (qada') and other matters?

Intentionally expelling semen during the daytime in Ramadan is a heinous sin and a grave transgression, and it invalidates the fast. Therefore, the day on which this occurred must be made up, and one must repent to Allah Almighty. The majority of scholars hold that expiation (kaffarah) is not required.