Question Summary:
From what age is qada obligatory?

Question Detail:

I would like to perform my missed ( kada/ kaza) salat from childhood. From which age I have to count it, for example from age of 12/13/13 years of old?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
In principle, salah becomes fard (compulsory) upon becoming an adult.[1]
A person is regarded as an adult in Shari’ah upon attaining buloogh, which is physical maturity.
The signs for physical buloogh in males are.[2]
 (1) Ihtilam (wet dream)
(2) Inzal (ejaculation)
The signs for physical buloogh in females are:
(1) Ihtilam (wet dream)
(2) Haid (period)
(3) Pregnancy
If one does not attain physical maturity or puberty by the age of 15, then Shari’ah considers the person to be an adult upon being 15 years of age according to the lunar calendar.
If you missed any fard salah or witar salah from the time you became baligh, you should make qadha (make up) for the missed salats.
 
And Allah Ta’āla Knows Best
Zakariya Memon
Student Darul Iftaa
Chatham, Canada 
Checked and Approved by,
Mufti Ebrahim Desai.
Daruliftaa.net