That's what makes it equitable.
- There are now more people spending money because they have disposable income. This is good for businesses.
- There is added incentive to work, because one does not lose income by starting a job.
- The people being made redundant by automation are given a cushion that will help as they figure out how to become economically relevant again. This is good for everyone, because there are fewer families forced out onto the streets, etc.
- There is, potentially, less of a bureaucracy to manage the distribution of existing welfare programs, assuming existing programs can be consolidated into the new basic income scheme. This is an attractive point for conservatives and libertarians.
There's no need for equitability here, although that's also something that is desirable within bounds. But I think few millionaires and billionaires will find a significant decrease in their standard of living if they have to pay more into the pot than they receive. Also keep in mind that the billionaires are billionaires because society provides a framework for them to accumulate and retain the capital that they have; for this reason they have an implicit debt and obligation to society.
With a scheme like this, one would replace a system full of loopholes (for the rich) and handouts (for the poor) with a simple flat system.
Everybody gets $x/yr, and everybody pays y% in taxes on all income after that (not just earned income). No deductions, no credits, no loopholes, no welfare state (other than the UBI).
What's somewhat clever about this is how it essentially balances out. The billionaire won't even notice the extra amount in their bank account, but there aren't many billionaires. Meanwhile the three jobs four kids single mom will be greatly impacted by this, which is the whole point.
I once calculated, based on what amounts to a back-of-the-napkin calculation based on a flat tax, that the inflection point would be somewhere in the $60-70k range for Canada. The US would be a bit higher due to the greater income inequality.
Yeah, that would be terrible. How could one survive?
_That_ is the sort of thing that could go away with a guaranteed basic income. At that point, you'd just have taxes, which do in fact behave as you describe.
And there are some programs that don't have marginal phaseouts. Each one is trifilingly small, but they may add up.
All sane countries with progressive taxation always apply the higher tax bracket only to the part of the salary that is in the bracket.
E.g. if the tax is 10% < $50k and 25% >= $50k, a $60k salary would have to pay 10% * $50k + 25% * $10k in taxes, and all wage increases increase net pay.
You don't understand how progressive taxes actually work. This simply doesn't happen. You can't make less money by making more money.
Or if you prefer to tax sales, with Z being the total amount of sales, priceX/Z. X/Z is the VAT rate.