I’m in Canada, maybe it’s different. You pay sales tax on a new house when you buy it, just like any purchase. Theres also land transfer taxes an other fees. When it goes up in value and you sell, you pay capital gains (unless it’s your principal residence, and then there’s an exemption). But until you sell or some other tax event, you don’t pay any tax on its increased value until such a tax event happened. At that point it’s assessed and you owe any tax on the gain. So if a tax event triggers some tax owing (like if using it as collateral triggered this), then later when you sell, you wouldn’t pay on that gain again, only on any gain since the last tax event.