He typed "245,000" into the first box. Then, he clicked the toggle that changed everything: “Is this an additional property?”

At sixty-four, Arthur wasn't looking for a kingdom; he was looking for a "pension in bricks." He had his eye on a terraced house in Manchester—a tidy two-bedroom listed at £245,000. To the uninitiated, the price was the price. But Arthur knew better. In the world of UK property, the "hidden ghost" in the room was always the .

Arthur leaned back. He realized the calculator wasn't just a math tool; it was a . It forced him to look at his "Yield." If he paid £10,000 in tax upfront, it would take him nearly eighteen months of rental income just to break even on the government's cut.