Thanks. I think I like your answer the best. I hadn't considered what happens when income situations change drastically during the course of a year. Let's talk about the case of a highly compensated individually who is foolishly living paycheck to paycheck. Let's say they those their job on July 1. With universal basic income, they'll keep getting some small amount of money to live on each month. They may have to downgrade apartments or locations, but they're still OK. With negative income tax, they've already exceeded the $60K phase-out for the year, so they get no help for the rest of the year, and since all entitlement social net payments have been phased out in favor of the NIT/UBI (including unemployment), they're fucked. They have half a year to go during which they get absolutely nothing before the NIT can kick in the next year.

So you'd need NIT on a resolution of months, not years, for it to handle the situation of unexpected job losses, and frankly I'd rather run screaming rather than have to handle taxes monthly.