"There's never a point where going up a tax bracket means you'd take home less money than you would have before your raise." I'm not sure if that's true, but I

"There's never a point where going up a tax bracket means you'd take home less money than you would have before your raise." I'm not sure if that's true, but I think the real issue is the loss of government support, particularly in terms of direct welfare. For instance, going up in salary by $10k a year wouldn't result in a lower paycheck due to taxes, but it might result in a loss of government supported child care, and might disqualify a family from government subsidized housing, either in direct benefits or access to a required set aside of "below market rents" (common in SF). Because those benefits may be worth well over 10k a year, you might experience a net loss by working. As a result, even if the tax rate is progressive, there is a transitional period for relatively low income people where the marginal "tax", if you include the loss of subsidies, is 100% or higher. As a result, there could be a powerful disincentive to work. I think this is part of the appeal of the UBI - it's "universal". Everyone gets it. You get your money regardless of whether you work. Yes, that could deter people from working, since they already get their money. But it might also encourage people to work more, since they will no longer lose those benefits at low salary levels that make working a losing proposition relative to direct government welfare.