How is the zakat calculated for an amount of 160,0 pounds, which is the proceeds from selling a machine that was bought for trade in January 2013 for 150,0 pounds, after its zakat was paid in July 2012, knowing that its sale took place in September 2013?

The obligation was to estimate the value of the machine at the time the capital became due (hawalan al-ra's al-mal), and to pay one-quarter of one-tenth (2.5%) of its value on the day the year (hawl) was completed. The purchase price is not considered. It is not permissible to delay paying zakat (definition) beyond its due time except for an excuse, such as the absence of the money, or waiting to give it to a deserving person, provided that the wait is short. So, if the value of the machine on the day the year was completed was 160,0, then one-quarter of one-tenth of it is 4,0. One-quarter of one-tenth is paid by dividing the amount by forty.