NIT is just moving the progressive tax system into negative values, which means you subsidize the poor but once you make enough money you won't get subsidized.
UBI is identical to NIT. The names are different framings of the concept, but the policy is identical and widely recognized as such, which is why the experiments frequently referred to tests of UBI are also the ones characterized as tests of NIT.
> NIT is just moving the progressive tax system into negative values
“Progressive” refers to marginal rates, which remain non-negative in NIT; NIT just has a flat personal refundable credit (which is equivalent to a flag annual payment) included. Which is exactly what a UBI is, except the payment in some forms of UBI is outside of the tax system, but that implementation detail is irrelevant: whether it's called a tax credit or a non-tax payment is still the same thing.
But I'd like to elaborate a bit here. UBI is not identical to NIT because the difference is marketing, not math. Most of the electorate's basis for evaluating a given policy is not to perform a mathematical comparison of two systems and checking whether they yield the same results. How something is done is as important in politics as what gets done.
Which is why, as I've pointed out, BI isn't like NIT at all. The difference is how the idea is going to get sold to the public, not what each taxpayer is going to end up contributing to the system as a function of their income.
But it's not even there, as proponents of both have stated that they are equivalent, and alternate names for the same thing, and they are marketed with the same arguments, and are widely acknowledged by their proponents to be names of the same thing. That is, the marketing isn't different, it's the same, both in content and on that the marketing itself recognized the equivalence.
That's still equivalent to an NIT (specifically, it's equivalent to adding the kind of refundable credit that creates an NIT, and reducing the standard deduction by the size of the credit, which may result in a negative standard deduction.)
Consider trying to introduce a universal health care system. You might say why do we need a system that subsidizes Jeff Bezos's health care? He can damn well pay for it himself, he might even agree since it's going to cost him less in terms of his tax contributions.
That's the equivalent of trying to sell NIT. Right out of the gate you have to not say "this is for everyone" but "it's just for the poor, but don't worry because...". That's what I mean by the marketing being different.
Of course with UBI the benefit is literally fungible, it's money. So it's really not like universal health care, but in the minds of a lot of people it is. They find it easier to accept the state providing a service if it's provided to them as well, even though it's a net cost center for them.
Humans.
1. https://mpra.ub.uni-muenchen.de/2052/1/MPRA_paper_2052.pdf
But this is explicitly what the proponents of BI want. It's as much about the optics as who pays for it. I.e. the idea is to create a program that draws its political support from everyone getting paid a check, similar to how Roosevelt enacted social security to include all citizens, even those who were millionaires and had no need for it.
Which is what sets it apart from Negative Income Tax.
Your argument that BI would be revenue neutral for some taxpayers and therefore we should just use NIT to avoid the sillyness of the government taking $1 from you just to give $1 right back to you isn't wrong, but it's missing what BI proponents are trying to achieve.
It's mainly about achieving roughly the same ends with different optics, and the comparison to Social Security is often brought up. Enacting any system like this is going to be politically difficult, and BI proponents believe that "everyone gets the same" is an easier sell than "this is another subsidy for the poor".
1. http://www.econtalk.org/archives/2017/01/michael_munger_3.ht...