How can usurious money be calculated and disposed of in a savings account that has been open since birth, knowing that the principal and interest are not fixed, and is it permissible to dispose of it through charity?

Money earned from savings accounts is prohibited interest (riba), and the husband must dispose of it. It is not permissible for him to benefit from anything other than his principal, based on the Almighty’s saying: "And if you repent, you may have your principal. Do no wrong, and you will not be wronged" (Al-Baqarah: 279).

If he is unable to determine the principal, he must exert effort and give away what he believes is most likely usurious interest, based on the Almighty’s saying: "So fear Allah as much as you are able" (At-Taghabun: 16).

Usurious money is disposed of by spending it on the public welfare of Muslims or giving it to the poor and needy with the intention of getting rid of it, not as charity. Usurious interest is absolutely forbidden, whether fixed or variable.