Is Zakat due on the original amount saved or on the remainder after expenditure, and are the profits from the invested amount included in Zakat?

If the remaining amount (twenty thousand) reaches the nisab and a year has passed over it, then zakat is due on this amount alone, excluding what was spent during the year. As for the profit that increased the amount due to trading, it is added to the principal when its year is completed, and all of it is subject to zakat, for profit follows the principal like the offspring of livestock.