I say, and with God's success: It is permissible to accelerate zakat for one or more nisabs after owning the nisab. It is permissible to pay zakat for several nisabs even if one only owns one nisab. For example: if someone owns (2500) dinars, which is the nisab, and pays zakat on (10000) dinars, this is allowed for him, and what he pays is zakat that will be due on him in the future. If he owns (15000) dinars at the end of the year, he will have paid zakat on (10000) dinars of it, and if he only owns (5000) dinars at the end of the year, then he has paid zakat for the coming years on (5000) dinars, and so on. The reason for this permissibility is that the first nisab is the basis of the obligation, and what exceeds it is dependent. Thus, if he owns more after the payment, what he paid earlier suffices as long as he is still the owner of the nisab. However, if he does not own a nisab at all, the payment is not valid; as for Ali (may Allah be pleased with him): 'Indeed, Al-Abbas (may Allah be pleased with him) asked the Messenger of Allah (peace be upon him) about accelerating charity before it is due, and he permitted that.' This is mentioned in Sunan Al-Darimi 1: 470, Al-Muntaka 1: 98, Sahih Ibn Khuzaymah 4: 48, and Al-Mustadrak 3: 375, as in Sharh Al-Wiqayah, p. 217, and Umdat Al-Riayah, 1: 284, and Tabyin Al-Haqaiq, 1: 275-276, and Allah knows best.