The man has to pay the Zakah on the amount over the 4,000 riyals for the years he is sure about, but he is not obliged to pay Zakah for the years he is not sure about, although it would be better for him to pay the Zakah for the years he is not sure about as a precautionary measure. (Part No. 9; Page No. 261) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.