> UBI-with-a-flat-tax gives a very nice curve It gives a family of curves, and as you say you have a knob you can turn... I don't have a strong opinion about

> UBI-with-a-flat-tax gives a very nice curve It gives a family of curves, and as you say you have a knob you can turn... I don't have a strong opinion about exactly what shape the curve should have, but I do have a strong opinion that it's probably important and I've noticed a tendency (first in myself!) for UBI proponents to be satisfied having checked the "it's a progressive curve" box without having looked carefully at whether it can produce the particular progressive curve we (more broadly) want. Edited to add: I suppose if we do find that we need people to be taking home marginally more for the first N dollars earned, we could add a rebate based on reported income. Small fraud ("I reported a little more than I actually made") winds up pretty bounded in the amount it can walk off with; larger fraud ("I invented 500 people who are reporting income") isn't that much bigger a concern than it would already be with a UBI since the maximum rebate is probably much smaller than the stipend that would otherwise be expected. Note that I'm not calling for this, just exploring the space.