How is the zakat for a pharmacy to be paid: Is it based on the purchase price or the selling price, and is zakat obligatory on expired medicines that cannot be returned or whose value is partially deducted upon return?

The value of trade goods must be assessed at the end of the year according to their selling price in the market at the time zakat (definition) becomes due, even if the selling price is less or more than the purchase price. As for government-priced medications, their zakat is calculated based on the selling price written on them. Expired medications are not subject to zakat, unless a supplier agrees to purchase them at a reduced price, or if they are customarily sold; in which case, zakat is obligatory on their selling price.