WASHINGTON — Here are the most important changes in the tax plan proposed Wednesday by President Trump.

Three Tax Brackets

The number of tax brackets for individuals is reduced from seven to three: 10 percent, 25 percent and 35 percent. That lowers the top rate by nearly 5 percentage points, easing the tax burdens on most Americans, including the rich. The Trump administration did not say where those brackets begin and end.

Double the Standard Deduction

Currently, individuals can deduct $6,350 and married couples can deduct $12,700 from their taxable income. Mr. Trump’s plan would double the standard deduction. That is intended to put more money in the pockets of the average taxpayers who do not itemize their deductions. It has the added benefit of simplifying the preparation of tax returns for more people.

Repeal of A.M.T.

The alternative minimum tax makes it harder for very rich individuals to game the tax system and pay less tax. It is an aggravating tax for the well-to-do, what Treasury Secretary Steven T. Mnuchin called a “complicated” additional system of taxation. The provision cost Mr. Trump an additional $31 million in federal income taxes in 2005, and now he wants to kill it.