When do I have to pay Zakat?

Zakat is due when all conditions of Zakat liability are met. 

1. The individual must be Muslim
2. The individual must be free (not a slave)
3. Wealth must be above Nisab and possessed for the span of one lunar year
4. Nisab is either the value of 85g of Gold or 595 g of Silver
   National Zakat Foundation follows the opinion that Zakat is due once a person’s wealth amounts to 595 g of silver (or the cash equivalent) 

There is another condition of adulthood and sanity which is not agreed upon. National Zakat Foundation follows the opinion that states the guardian should pay Zakat on the wealth of someone who is below the age of puberty, or whose sanity is questionable.