Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Fatwa No.5454
Fataawa Ramadhaan – Volume 1, Page 390, Fatwa No.349
Question: I am a student in my third year at secondary school. The end of year exams are due to take place during Ramadhaan, in shaa.-Allaah. As you know, during the days of the exams a student requires full concentration and hard work, particularly since the exams take place over consecutive days, one after the other. I find that fasting requires some element of ease/rest and sleep. So is it permissible for me not to fast during the exam days, and then make up the fasts [which I missed] afterwards?
Response: It is not permissible for you not to fast [during Ramadhaan] for that which you have mentioned, rather it is haraam upon you [to refrain from fasting] since that which you have mentioned does not qualify/excuse you from fasting in Ramadhaan.
And with Allaah lies all success, and may Allaah send prayers and salutations upon our Prophet Muhammad ﷺ and his family and his companions.