What do I actually pay Capital Gains Tax on?

Capital Gains Tax applies when you sell or dispose of an asset that has increased in value. The main ones are: residential property that isn't your main home (second homes, buy-to-lets, inherited property); shares and investment funds held outside an ISA; cryptocurrency; business assets including goodwill; and personal possessions worth more than £6,000, such as jewellery or art. Assets that are exempt include your main home (in most cases), anything held inside a Stocks and Shares ISA, your car, and UK government bonds (gilts). The gain is calculated as the sale price minus the original purchase price and any allowable costs such as legal fees or improvements.