What is the best way to tax high-net-worth individuals (HNWI) in Europe effectively? Their wealth has grown over recent decades, but they are subject to lower effective tax rates than the average citizen. This brief reviews the history of net wealth taxes and comes up with five lessons for modern approaches to effectively taxing high-net-worth individuals. It shows that earlier wealth taxes raised limited revenue and failed to tax these individuals because of the narrow tax bases and low thresholds, not because of large-scale mobility. Modern systems should adopt broad tax bases without carveouts, target extreme wealth with high thresholds, use minimum-tax top-up mechanisms, include credible anti-exile rules, and leverage today’s transparency tools to tax high-net-worth individuals effectively.