It is permissible to advance the zakat for a year or more after owning the nisab; it can be paid at any time without being restricted to a specific date, provided that the person is the owner of the nisab. Therefore, it is valid to pay it before a year has passed on the nisab, for the reason is the growing wealth; wealth is the essence, and growth is a characteristic of it. Thus, it is permissible to pay it after the existence of its essence, and because the growing wealth is the reason for the obligation of zakat, and the year is a condition for the obligation of payment. If the reason exists, the payment is valid even though it is not obligatory. Therefore, when the nisab is present, the payment is valid before the year; as narrated by 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 advancing the charity before it is due, and he permitted that." This is found in Sunan Al-Darimi 1: 470, Al-Muntaka 1: 98, Sahih Ibn Khuzaymah 4: 48, and Al-Mustadrak 3: 375.