It is difficult for me to calculate the zakah precisely, so I estimate it and pay an extra amount to be safe; is my action prescribed?

Question:
Honorable Shaykh, may Allah grant you success. He says: It is difficult for me to calculate the zakah precisely for several reasons, due to the variety of my earnings, so I estimate it and pay an extra amount out of caution and to clear my conscience. Is my action permissible?

Answer:
A quarter of a tenth is paid from money. As for trade goods and merchandise, you value them at their worth at the end of the lunar year and pay their zakah. Estimation is not sufficient; estimation is not sufficient. The actual amount is required. Yes. For example, if you have billions, you say, “By Allah, I do not calculate it; I estimate it,” but this amount is sufficient. Do not say, “This is not enough.” You must pay a quarter of a tenth. Whether the money is little or much, if it reaches the nisab, zakah is obligatory on it, and estimation is not sufficient. Likewise, if it increases, you must know the exact amount of the zakah. Yes. Estimation and guessing are not sufficient for it. Yes.