I can try to give you a theoretical tax breakdown using real numbers.

In 2018, the household income quintiles were as follows (https://www.taxpolicycenter.org/statistics/household-income-...)

Lowest quintile mean: $13,775

Second quintile mean: $37,923

Third quintile mean: $63,572

Fourth quintile mean: $101,570

Highest quintile mean: $233,895

There were about 159M employed persons in the US in the most recent high (https://tradingeconomics.com/united-states/employed-persons), about 50% of the US population. We want our UBI to cover everybody.

To make this simple, because quintiles comprise an equally populated group of people, let's imagine that instead of there being ~32M people per quintile, that our nation has 10 people, where 5 people don't work, and each of the remaining 5 falls into one of the quintiles.

If we wanted to define a UBI of $18,000 per person, we need to somehow come up with $18,000 * 10 == $180,000 to distribute to everyone equally.

If we fund this progressively, each individual would have to pay:

Unemployed #1: 0 (statistically, a child)

Unemployed #2: 0 (statistically, a child)

Unemployed #3: 0 (statistically, a retiree)

Unemployed #4: 0 (statistically, a retiree)

Unemployed #5: 0 (statistically, a disabled person or stay-at-home caretaker)

Lowest: $8,000

Second: $12,000

Third: $21,000

Fourth: $36,000

Highest: $103,000

Total revenue: $180,000

Then consider that everyone here is receiving back 18,000 under the UBI. The highest quintile earner’s net take-home is, thus 233,895-103,000+18,000 == $148,895, which effectively renders their effective tax rate approx 36%. If you run this breakdown across all quintiles:

Unemployed #1-5: $0 - $0 + 18,000 == $18,000

Lowest: $13,775 - $8,000 + $18,000 == $23,775 (effective tax -73%)

Second: $37,923 - $12,000 + $18,000 == $43,923 (effective tax -16%)

Third: $63,572 - $21,000 + $18,000 == $60,572 (effective tax 6%)

Fourth: $101,570 - $36,000 + $18,000 == $83,570 (effective tax 18%)

Highest: $233,895 - $103,000 + $18,000 == $148,895 (effective tax 36%)

You'll notice that the top 2 pay a tax rate that’s comparable to today’s. We wouldn't necessarily need to increase everyone's taxes by the above amount, because there's some wiggle room in the Federal budget. Examples: we can probably eliminate Social Security (which would just be replaced by the UBI), EITC/CTC (basically already a BI), and food stamps (ditto). Medicare, which is an in-kind benefit, can either be eliminated, or it can continue to exist but be paid for by the UBI. Ditto Medicaid.

Also notice that because the lowest quintile still ends up with more than the unemployed person after their taxes, there isn’t a disincentive to work.

This math also assumes that we're giving people $1,500 per month, and also assumes that children will receive the same amount as adults — a UBI may only pay $1,000 per month to adults, and $500 per month to children, in which case the effective tax rates would be lower.

This math also assumes there is 0 VAT. This math also ignores payroll taxes, which account for 35% of the current Federal revenue.

We can play with different levels of progressivity and generosity, but the idea is the same. We can scale up from single-person quintiles to million-person quintiles, but the percentages don't change.