There are two conditions for Zakat to be obligatory on the wealth.
1. Being in possession of Nisab i.e. possessing property in excess of a minimum exemption limit.

2. On completion of one Lunar year on the wealth. According to Hanafi if a person possess wealth equal to or in surplus of Nisab in the beginning and at the end of the lunar year, (even though in between the year, the wealth was less than the Nisab), Zakat is obligatory, but if at the end of the lunar year if the wealth is less than the Nisab (though one had wealth equal to or in surplus during the year) zakat is not obligatory. According to Shafie the passage of one lunar year is a must on the wealth (Nisab) (in Hanbali almost a year).

The zakat is calculated on the day on which a year is completed on that wealth (Nisab). Nisab: Zakat is paid on the surplus of wealth which is left over after the passage of a year(Lunar Year). It is thus a payment on the accumulated wealth, leaving our animal and agricultural yield. Zakat is pain at almost a uniform rate of 2 1/2%. The minimum standard of surplus of wealth over which Zakat is charged is known as Nisab. It differs with different kinds of property. In case of silver it is 52 1/2 Tolas (634 grams), in case of gold it is 7 1/2 Tolas (88 grams). The Nisab for cash is the same as that of gold and silver.

لماذا يخلق الله المعاقين والفقراء - د ذاكر نايك Dr Zakir Naik

أيهما أفضل الدفن أم الحرق"ذاكر نايك"- which is better burn or bury