Is Zakat obligatory on a house that was purchased for investment purposes, while owning another house for dwelling? And is Zakat calculated based on the purchase price or the price of the house after a full year has passed?

If a Muslim buys a house with the intention of trading (selling for profit), then zakat is obligatory on it. It should be appraised at the end of each lunar year, and then zakat on its value, which is one-quarter of one-tenth (2.5%), is to be paid. However, if it was not intended for trade at the time of purchase, then zakat is not obligatory on it, even if the intention to trade it arises later.