It's certainly a progressive rather than a flat tax, though flatter and without deductions, much like Reagan's changes.
Your example is wrong, there's no tax on the first $25,000 (standard deduction), 10% on the next $100m, 25% over that. Your example, taxes would be $7,500 10% of the $60m over the exemption, not $25m.
The plan was initially developed by the House of Representatives Republican Study Committee. And obviously it's only a portion of proposed reform, which includes lowered corporate rates, elimination of the AMT, 15% capital gains and repeal of the death tax, since the option of using the old system still exists.
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Oh, yes ... the rest of the tax reform package looks pretty good, too.