Note that the US already effectively has a wealth tax, because of how long-term capital gains tax is computed. Let's say you had $100M from a successful startu

Note that the US already effectively has a wealth tax, because of how long-term capital gains tax is computed. Let's say you had $100M from a successful startup in the first dotcom bubble (2000-08-14). You sell all your stock (unrealistic, but ok), put it in VTSMX (33 -> 83), and you're up to $250M twenty years later. Then you sell it all. Nominally that's a 4.7% annual return, but there was also inflation: your $250M today would have been worth $167M in 2000, not $100M. That's about a 2% inflation rate, and your real return was 2.7%. Another way to think of this is, you had 100M DOLLAR_2000s, which is equivalent to 150M DOLLAR_2020s. Your real gain was from 150M DOLLAR_2020s to 250M DOLLAR_2020s. The IRS ignores inflation, however, and charges you capital gains on the whole nominal gain. Instead of taxing you on a gain of 100M DOLLAR_2020s they tax you on 150M DOLLAR_2020s. This is nearly equivalent to: * Tax people only on their real gains, after inflation. * Charge a 0.4% wealth tax (2% inflation * 20% long-term capital gains) Which makes me think that "even a .5% wealth tax would start to keep founders away from a state or country that imposed it" is probably overstating the claim, since the US is very popular for startup founding and has an effective wealth tax nearly that high.