In case...
In case, therefore, a person is not aware or forgets that it is the month of Ramazan and makes an intention to observe some other fast that fast will be considered to be the fast of Ramazan. 1565. If a person knows that it is the month of Ramazan and intentionally makes an intention of observing a fast other than the fast of the month of Ramazan his fast will.not, on the basis of obligatory precaution, be reckoned either a fast of the month of Ramazan or the fast for which he made the intention.
If a person does not know or forgets that it is the month of Ramazan, and takes notice of this before midday and if he has performed some act which invalidates a fast, or takes notice of it after midday that it is the month of Ramazan, his fast is void. However, he should not perform any act till sunset which invalidates a fast and should also observe qaza of that fast after Ramazan. And on the basis of obligatory precaution the same orders apply.
if he takes notice of the matter before midday and has not performed any ad, which invalidates a fast. 1571. If a child reaches the age of puberty before the azan for dawn prayers in the month of Ramazan he/she should observe fast and if he/she reaches the age of puberty after the dawn Azan, the fast of that day is not obligatory for him/her. 1572. If a person who has been hired to observe the fasts of a dead person observes recommended fasts there is no harm in it.
However, if a person has to observe qaza of fasts or some other obligatory fasts, he cannot observe recommended fasts.