the tax burden is distributed unfairly
So 98% of rich people (150k+) paying for about 70% of income tax, 50% of the middle ($35k - $150k) paying for about 20%, and less than 30% of the poorest income bracket paying about 10% is not progressive enough? Progressive taxes gives the illusion that taxing some people less supports the existence of residential wealth and taxing some people more bolsters income collection from those with "wealth to burn." Historically, neither of these assumptions have padded out. If anything, progressive taxes, by being able to grow quicker than a flat tax, have demonstrated two things: there is a ceiling where you actually stop gaining revenue from your taxation level, and neither attempts to favor the poor by being them less burden nor punish the rich by giving them more burden has causes the poor and rich to coalesce into the middle. The poor, for their own shortcomings, remain poor and the rich, for their own successes, remain rich; the middle either stays or goes either way, usually down. Progressive taxes don't change this in good ways, either, though I would never recommend trying to engineer society in this fashion (we're sticking with the goal as "increase tax revenue").
>>1
Despite that, a flat tax will not solve anything on its own. Getting rid of these special taxless entities that allow statistics and I to read numbers like "98%" "50%" and ">30%" is a start in some direction; but the basic reality is that no amount of taxation will be able to finance either our debt (as it is) or spur our economic recovery. Especially if the money is constantly spent and then
overspent as it is collected. In fact, collecting taxes is entirely the wrong solution to look to in my opinion since it precludes the existence of wealth to collect.
What we need is to do is promote the private sector into generating and accumulating wealth again. You can always legitimately create more which is why that will eventually produce the solution to the economic woes and debt at the same time (bar spontaneous forgiveness by our debtors).