Is Zakat calculated on the total value of goods purchased for trade (200,0 dinars in January and 100,0 dinars in October) at the end of the year, or is a new year initiated for the goods purchased in October?

The owner of trade goods must pay zakat on them according to the origin of the capital with which they were purchased. One should consider the time of possessing the money used to buy the goods. If he possessed all of it at one time, then its zakat is due when a full year has passed since he possessed it at that time. However, if he possessed some of it first, and then acquired the rest from a source other than the growth of the original capital (such as inheritance), then the zakat on the acquired money is due when its own year passes, or it can be paid along with the zakat on the original capital.