Zakah on Trade Stock
Q: Does a year need to pass on my trade stock before I pay zakah on it? If the value of an item decreases after purchasing it for trade, do I still need to pay zakah on it?
A: “There is no zakah on items unless they are for trade and the value of them reaches the threshold (nisab) of either gold or silver and the value of them is added to gold and silver… There is no stipulated threshold for items because the Shariah never transmitted one so it resorts to the value and if they are valued with either gold or silver then consideration is with the value and they are added to gold and silver.”
In short, a year does not need to pass on the actual items themselves because the concern is with the value and reaching the threshold on the day zakah is due.
Answered according to the Hanafi School by Shaykh Bilal Brown
 (Al-Ikhtiyar, Chapter of Zakah of Gold and Silver).