Who must give zakat?
Every Muslim, who is sane, has reached puberty, and owns a wealth that is at least as much as the amount of nisab is responsible for giving zakah of their wealth every lunar year that begins after one year having attained to that wealth.
Nisab is the minimum amount of wealth for which the zakat is due. It is 85 grams of gold or 595 grams of silver or equal amount of money or commodity.
Lunar year is the basis for zakat and that is 354 days.