Could taxes be simplified?
The individual tax code should be something simple to understand and fair.
Start with a universal basic income. For point of discussion, a starting point is $15K/year to each US citizen who has reached 21 years of age or attained a high school diploma. The rate can step up again at 65 years of age. In exchange for granting this, several forms of government assistance can be eliminated (though I'd be willing to accept arguments against removing those). That would include social security, federal housing assistance, federal college financing, food stamps, along with eliminating the agencies responsible for managing those programs.
In particular, this income should be universal - not means tested, and not specifically forced to any particular spending requirements. It should be paid via direct deposit to a bank, partnering with banks to make services available to currently un-banked populations. Banks participating in the feature should not be allowed to charge monthly fees on the accounts receiving the deposits (most banks offer a checking account with no fees if your paychecks are direct deposited, this should satisfy that requirement).
Once the basic income is established, tax all personal income at a flat rate. For sake of discussion, this could be 25-30%. At 25%, an individual making $60K/year would have an effective rate, after the basic income, of 0%. $100K would be 10%, and $1M would be 23.5%. (at 30%, the break even point would be $50K, higher than 30 might be acceptable as well). This rate should cover all personal income, including salary, capital gains (short and long), carried interest, etc.
In exchange for the lower overall tax rate, all deductions will be eliminated - charitable deductions, mortgage interest, etc all gone. On top of that, because the first step eliminated social security, that tax is gone as well, though elimination of that could possibly justify a slightly higher flat rate. It could probably go as high as 35% while still lowering taxes for most Americans.
One last thing. I'd replace the large number of options around tax deferred savings with a simplified account. You can deposit up to 10% of your income in the account each year and it is deducted from your taxable income. In that account it can grow tax free, but all withdrawals from the account ever will be taxed at the income rate on withdrawal. There should be no minimum age or other requirements focused around when that money can be withdrawn without penalty. Withdrawal is a simple matter of paying the tax and taking the money out.
So... can someone tell me why this wouldn't work out?