A classical NIT preserves incentives to work while a UBI does not.
Isn't it the opposite? With NIT, if you're below the level, you'll make the same amount regardless of whether you work or not, whereas with UBI you just add it on top of whatever else you earn.
I'm actually not sure which one is best. I'd prefer UBI if feasible, but the amounts of money you need to raise to pay for it is pretty daunting.
With NIT, you don't earn the same regardless of whether you work, but would be closer than with a UBI.
For NIT with a $30k standard deduction for example, and NIT rate of 50%, $0 becomes $15k, $10k becomes $20k, $20k becomes $25k, and $30k is $30k.