Failed to Fast Ramadan When 18 Years Old
29-10-2002 | IslamWeb
Question:
When I was 18 years old, I did not fast in Ramadan and no one told me that I must fast in Ramadan. Shall I fast it now? Tell me what I can do?
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad 
is His slave and Messenger.
It is mandatory on you to make up the days you missed fasting and which you should have fasted in the first place. If you know their number, the matter is settled. But if you do not know their number, then you should fast until you become certain that you are free from liability [i.e. made up for all the days that you broke fasting]. Know that the signs of puberty are as follows:
1) Having wet dreams. So when the male ejaculates and when the female has vaginal secretions due to sexual desire they have reached the age of puberty.
2) Growing of pubic hair which is hair that grows in the area surrounding the sexual genitals. If this hair grows in this area then the male/female is considered to have reached the age of puberty. So, if any of these two signs appear the person is considered by Islamic Sharee’ah as having reached the age of puberty regardless of whether he has reached the normal age which is fifteen or eighteen according to the Shaafi'i and Hanbali Schools of jurisprudence.
But the Maaliki and Hanafi Schools consider the age of puberty to be eighteen. The Hanafi School is of the view that the age of puberty for the woman is seventeen only if the two signs stated above do not appear.
Here we want to draw your attention that whoever deliberately abandons fasting in Ramadan and does not make up the missed days until the next Ramadan begins, then such person should feed a poor person for every missed day as expiation besides making them up later. This ruling applies to the one who delays fasting knowingly and without any legal excuse such as illness, journey, etc. If one delays fasting due to ignorance or forgetfulness, then there is no expiation due on him. This opinion is stated clearly in the Shaafi'i School and also from a group of Muslim scholars.
Allah knows best.