Should the Zakah be paid after subtracting

A: Zakah is due on grapes when it matures and reaches Nisab (the minimum amount on which Zakah is due) which equals five Wasaq and one Wasaq equals 60 Sa`s (30,320 kg) of the Sa` of the Prophet (peace be upon him). The due Zakah is to be paid in raisins, for the Hadith related by Abu Dawud on the authority of `Attab ibn Usayd (may Allah be pleased with him) that he said: The Messenger of Allah (peace be upon him) commanded to estimate vines (for collecting zakah) as palm-trees are estimated. The zakah is to be paid in raisins as the zakah on palm-trees is paid in dried dates. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.