Tax reform is the process of changing the way taxes are collected or managed by the government and is usually undertaken to improve tax administration or to provide economic or social benefits. Tax reform can include reducing the level of taxation of all people by the government, making the tax system more progressive or less progressive, or simplifying the tax system and making the system more understandable or more accountable.

The 9–9–9 Plan was a tax proposal that was a centerpiece of Herman Cain's 2012 campaign for the Republican Party's nomination for president of the United States. It was introduced in August 2011. The plan called for the replacement of all current taxes, such as the payroll tax, capital gains tax, and the estate tax, with a 9% personal income tax, 9% federal sales tax, and a 9% corporate tax.