Zakaat - Rules and modern issues

The wealth should meet the prescribed criterion

Zakaat becomes compulsory only when the wealth meets the criterion prescribed by the Shariah.  The Holy Prophet (Sallallahu alaihi wa sallam) has fixed the criteria for gold, silver and animals.  There is a Hadith in Sunan Daraqutni about the criterion for gold:

Translation: Hadhrat ‘Amr bin Shu’aib narrates on the authority of his father, he from his grandfather, and he from the Holy Prophet (Sallallahu alaihi wa sallam) that He said: There is no Zakaat on less than 5 camels.  There is no Zakaat on goats less than 40.  There is no Zakaat on cattle less than 30.  There is no Zakaat no gold which is less than 20 Mithqaal.  There is no Zakaat on silver less than 200 Dirhams………In the harvest which is through natural water, it is 10 percent and in the harvest which is through the water of wells, etc., it is 20 percent.  (Sunan Daraqutni, Hadith No. 1925)