Advocates of a constitutional amendment that would apply a 4 percent tax on all annual individual income over $1 million argue that similar taxes in other states have had little impact on the migration of millionaires, citing the research of Cornell University Associate Professor Cristobal Young, which suggests that “millionaires’ taxes” enacted in other states similar to the one being proposed in Massachusetts have had little impact on millionaire mobility. This paper demonstrates that he drastically undercounts millionaires, and outlines several ways in which he and tax advocates underestimate the number of people who will at some point in their lives be subject to a so-called millionaire’s tax and tax flight trends.