I agree that UBI makes sense from a PCT viewpoint, but I don’t think any of these experimental programs do it optimally. I have argued that the “U” is more important than the “B” and the “I”, though they are important too.
My approach would be to find an income level that would allow a person or a family to acquire livable housing and to procure enough food for survival. I suppose those define the socalled “poverty line”. That defines the “Basic Income” part. That money would go to the unemployed and to the billionaire equally, and would be included in their taxable income. The zero tax cutoff would be well above the UB Income, and there would be no clawbacks for someone obtaining a paying job.
The main objection I see raised against UBI is that it would cost the Government too much. The cost actually could be any number, positive or negative, quite apart from the boost it would give to employment and commercial profits, both generators of tax revenue. For one thing, the cost of government administration would be greatly reduced by the elimination of any need for unemployment insurance or the salaries of people who check that welfare recipients don’t earn too much to qualify. How much it would actually add to the annual deficit would depend entirely on the income tax schedule, and could be positive or negative overall.
That’s a brief sketch of how I think it should be done, but however it actually is done, it’s better for the people and for the economy than no UBI at all.