Is it obligatory to dispose of all usurious interest accrued from 1986 to 2005, or only the interest accrued in the last two years before it was stopped?

It is not permissible to deposit money in usurious banks except out of necessity to preserve it in a current account and without interest. The interest taken on such a deposit is forbidden and must be disposed of by spending it on public interests and charitable causes. This disposal is obligatory upon whoever engaged in usury.

As for the heirs, some scholars permit them to benefit from this money, because that which is forbidden due to its earning – like usury – is forbidden only to the earner.

Sheikh Ibn Uthaymeen, may Allah have mercy on him, said: "That which is forbidden due to its earning is forbidden to the earner, such as usury. If a person who dealt in usury dies, his money is lawful for his heirs."

Based on this, there is no harm for the heirs to benefit from the usurious money earned by the deceased, but any interest added to the money after the death of the deceased must be disposed of. This is the preferred opinion.