Is there a specific time for giving zakat?

Zakat can be given at any time of the year. As with fasting and pilgrimage, the lunar calendar is used to determine whether a full year has passed over the nisab amount of wealth. Zakat must be given as soon as it becomes obligatory. There is no need to wait for a specific lunar month or for Ramadan. Those who are obligated to give zakat should do so as soon as they become liable. This is because zakat is a duty of servitude, and debts should be paid off as soon as possible. (Ibn Abidin, Radd al-Muhtar, 2/271-272)

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu