Is it obligatory to pay Zakat for past years in which it was not paid, and is it permissible to pay a fee to obtain the necessary bank statements for calculation, and what is the correct method of calculation given the difficulty of accurately determining the amount and the presence of Riba-based interest, and is it permissible to give a larger amount in charity than the obligatory Zakat if that leads to asking for money from an apostate father, and is it obligatory to give in charity the value of accumulated Riba?

Usurious gains are ill-gotten wealth on which zakat is not obligatory. One must dispose of it by spending it on Muslim welfare or giving it to the poor and needy. The holder does not own it unless they are poor and in need, in which case they may take from it according to their necessity.

For paper currency, there are two conditions for zakat to be obligatory: reaching the nisab (the equivalent of 85 grams of gold or 595 grams of silver) and the completion of a full Hijri year (hawl). Whoever possesses the nisab and a year passes on it, zakat becomes obligatory on them. If one has not paid zakat for years, they must pay the zakat for all past years through diligent estimation. The expenses of calculating zakat are incumbent upon the wealth owner.

The amount of zakat is one-quarter of one-tenth (2.5%), which can be calculated by dividing the wealth by forty. The need for the non-Muslim father's money to pay delayed zakat is not taken into consideration. It is permissible to benefit from the father's money, even if he is an apostate, if the daughter is in need. It is advisable to contact Islamic centers or scholars for direct inquiries.