Is Zakat obligatory on an inheritance that the heir has not received until reaching the legal age, and is it obligatory retroactively from the date of the parents' death? What is the ruling on Zakat for a monthly sum inherited from the state that is spent regularly? And is money taken from the share of relatives in the inheritance of a house sold by virtue of positive law considered legitimate money on which Zakat is obligatory?

If you are an adult, zakat is obligatory upon you, subject to its conditions. If you are currently unable to withdraw and dispose of the money, then zakat becomes obligatory when you take possession of it, for one year. This is the view preferred by the Maliki school and was the fatwa given by Ibn Uthaymeen regarding minors' money deposited in the bank. However, if you are not an adult, zakat is also obligatory according to the majority of scholars, and your guardian should pay it on your behalf.

Gold and currency are subject to zakat when a full year passes while you have owned them (from the time of inheritance or possession). As for real estate, there is no zakat on it. What matters in zakat is the passing of a full year. Whatever has had a full year pass on it, its zakat is due if it reaches the nisab (minimum threshold), and whatever was consumed during the year is not subject to zakat. Regarding your share of the price of the inherited house, if it is your legitimate share, then there is no problem. If it is in excess, it is not permissible to take it without the consent of the other adult and rational heirs.