Unrealized gains are, essentially, ­income—just ask the bankers who accept them as collateral. But Congress has never touched them. If it did, the Roberts court has signaled it wouldn’t play along. “We all thought that there’s no way the Supreme Court’s going to say that income only gets measured at sale,” says Galle, who had helped craft one of Cohen’s efforts to tax unrealized gains. But the court’s 2024 ruling in Moore v. United States made clear that it would do just that. The takeaway is that a federal tax on either wealth or paper gains will require another constitutional amendment, the likelihood of which, Dale says, “seems to be something slightly below zero.”

Which helps explain why voters and lawmakers are exploring local options like New York City’s pied-à-terre tax (which passed) and San Francisco’s “Overpaid CEO” ballot measure (which didn’t). Every such move begets a flurry of op-eds warning that the “golden geese” will fly off to another city, state, or even country, as some of Dale’s clients have. History suggests few actually will. As an analysis from the Center on Budget and Policy Priorities notes, California already has the nation’s highest marginal tax rate, but boasts the second-lowest rate of out-migration among households earning more than $200,000. Then again, we’re talking about billionaires.