What is the ruling on someone who has not paid the zakat on his money deposited in an Islamic bank for twenty years, under the pretext that he heard that money saved for educating children is not subject to zakat, and he now wishes to pay it but not in one lump sum due to his need for the money to educate and marry off his children? Should he pay the zakat on this money this year and the remainder in installments?

A Muslim must pay Zakat for all past years in which the money reached the nisab, because Zakat does not lapse with the passage of time.

If one can determine the amount of money for each year, they must pay a quarter of a tenth (2.5%) for each year. If unable to do so, they should estimate the wealth for the unknown years, then pay a quarter of a tenth for each year in which the money reached the nisab. Then, the entire Zakat amount should be distributed to the poor and needy.

The amount must be paid immediately if one is able to, and delaying it is not permissible. Reaching the nisab and the passing of a full year (hawl) obligate Zakat, regardless of the owner's circumstances. Zakat does not lapse under the pretext of educating children or their unmarried status, nor are these valid excuses for delaying or paying Zakat in installments. Zakat is a source of blessings and growth.