How does one pay the zakah of one who has been neglecting it for many years?

The questioner : The questioner says: Honorable Shaykh, a man is advanced in age, and since Allah made him wealthy, he has not paid the zakah on his money. He does not know now how many years he has neglected the zakah, nor the amount of money for which he should pay it. Knowing that the money is in a riba (usury or interest) bank, what is the method of paying the zakah? First, we ask: Has this father been guided by Allah, and does he wish to pay the zakah?

The Shaykh : Let it be so that he has been guided by Allah the Exalted and he wishes to pay or discharge the past zakah. The answer to this is that the matter is easy. He can go back to the past accounts and look at the account for each year individually, and it will become clear to him at that time how much the zakah is. For example, if this amount of money was one hundred thousand in the year 1400, how much does he pay? He pays zakah on one hundred thousand: two thousand and five hundred. Good. In the year 1401, it went back to fifty thousand, he pays zakah. One thousand and two hundred and fifty. And two hundred. In any case, half of what came before. If this amount of money increases in 1403, he increases the zakah, and so on. As long as the account exists in the bank, the accounts are available because they are recorded and calculated each year according to its due. So I say to this person whom Allah has granted guidance and who wishes to pay the zakah on his money: I say, go back to the bank and you will know the amount of the account. Then I say a second time: if this person who has placed his money in the bank takes riba from the bank, then that is forbidden for him and not permissible for him. But if he placed it without taking riba, there is no harm if he is in need of it. But without need, he should not place his money in the bank, because that involves the growth of his money and an increase and expansion in his trade. Yes.