How does a businessman pay zakat on his wealth if his income is substantial, but the money does not remain with him for a full year, as he immediately uses a large accumulated sum to purchase assets such as buses, trucks, or hotels?

Zakat is obligatory on items prepared for trade as commercial goods. They are to be appraised, and a quarter of a tenth [2.5%] is to be given after one year has passed on the money with which they were purchased. As for items prepared for rent, there is no zakat on their intrinsic value. Rather, zakat is on their income if it reaches the nisab (minimum threshold) and a year has passed on it, either by itself or when added to other funds. However, if the intention behind renting is to evade zakat, then zakat becomes obligatory on the income, treating the act contrary to its intended purpose.