I've calculated what kind of taxation it would take to provide UBI to the same amount as current federal minimum wage - $30,160 per household - to all adults in the USA, assuming the existing income distribution. If we're talking about a flat tax, with the UBI part of the income not taxed (which translates to an effective progressive tax on total income including UBI), we'd be talking about a 55% tax rate on non-UBI portion.
The effective total rate would range from 0% at the very bottom to 48% for people earning $200k, with a linear increase in between (my model assumes that there's no incomes above $200k, because I didn't find readily accessible information on income distribution above that number). All people getting ~$50k or less would receive more from the system than they'd be paying into it. Those earning $75k would see ~$12k of that taken by the system.