For a large number of people, it is impossible to tell. What you have to look at is the effective tax rate, not the marginal tax rate. The effective rate is what you actually pay as a percentage of your income, and is affected by deductions, exemptions, tax credits, etc. Without knowing what deductions would be available, what exemptions would exist (if any), the number and size of any tax credits, etc., it is impossible to determine if anyone would be better off or worse off.
I have to assume based on what has been written so far that most higher income people would be worse off, as I believe a key part of the plan is to reduce or eliminate most deductions and credits. Thus, they may have a lower top marginal tax rate, but a lot more of their income would be subject to that rate, and they would have fewer credits to offset those taxes.
No, its not at all impossible to project. Take your last tax return. Look at AGI (adjusted gross income). From that subtract either your standard deduction per your tax return OR the total of your mortgage interest and charitable contributions, assuming conservatively that this is all you’ll be able to take. Subtract your personal exemptions. That will give you taxable income. Multiply by rates shown in the plan. Keep in mind that if you are married, first 50K is at 0%, next 50 is at 10%, next 200K is at 20% and so on.
Compare that amount to what you paid. You will either WIN or LOSE.
I looked at this the simplest way I could. I took total income, no deductions, not even for mortgage and used Trump’s rate schedule. Under this system, I would still pay 25% less than I did last year.