The US population has 199M adults[1]. Let's say a decent basic income is $40k. That's 8 Trillion that the government has to find every year.
The US federal tax revenue was of 3.86 Trillion last year[2]. Half of which comes from individual income, and another third from payroll taxes. This is before the effects that UBI will have on the economy.
Maybe my 10 minute research is wrong? It seems like a quite central piece to address in an article promoting UBI.
[1]: https://www.wolframalpha.com/input/?i=number+of+adults+in+th... [2]: https://www.whitehouse.gov/wp-content/uploads/2020/02/budget...