I will admit... Trump's 15% flat tax on all small businesses is pretty awesome.
Perhaps if small businesses aren't able to use some of the tax loopholes big business are, it is awesome. Oregon corporate state tax rate is 7.60%. This is neither the highest nor the lowest rate in the Nation. Federal tax rates are currently anywhere from 15% to 38% depending on corporate income and where it falls on the eight different corporate income brackets.
Nike, an Oregon based corporation got a major tax break in 2013 which continues for 30 years. Nike threatened to move out of state in order to secure this tax break from then Governor John Kitzhaber. This is the same Governor who is currently under federal criminal investigation for influence peddling. He was forced to resign in 2015 during his 4th term of office.
Big corporations make tax break deals with government that greatly reduce their tax burden. In addition to tax breaks they use a variety of loopholes, write offs and special deals which further lower their taxes. PGE is often exampled as a corporation that does not pay corporate taxes. A "Tax Extenders" Provision Has Allowed Highly Profitable PG&E to Pay Zero Taxes the Last Seven Years.
The bottom line is the tax laws in the U.S. at both the state and federal levels for corporations is so complicated that despite tax rates, they pay little or no actual taxes.
A flat tax generally means there are no deductions, tax breaks or loopholes. If this were true, a flat tax of 15% on corporations would actually increase their tax obligation.
I don't believe for a second that Donald Trump would institute a tax plan that decreased his profit margin by increasing his taxes. A few possibilities exist, Trump's U.S. holdings are bankrupt to the point that there are no profits, almost all of his revenue producing concerns are tax-sheltered and off-shore or he knows he can continue to manipulate the benefits of Real Estate deductions to the point that he will not suffer any additional tax burden....that would be additional to almost nothing.
Do you still have questions as to why he doesn't release his income tax filings?