A tax cut is a reduction in the rate of tax imposed by a government. Whether a given tax cut will increase or decrease total tax revenues is often discussed and debated by both economists and politicians.

Economic theory
In recent decades, most "supply-siders" in the United States have been Republicans (though the largest individual tax cut was initially proposed by President Kennedy from the Democratic Party) with the belief that cutting the tax rate would stimulate investment and spending, with overall beneficial effects (including replenishment of some lost tax revenues
See also: Trickle-down economics and Reaganomics

Tax cuts in the United States
The 2006 Federal Budget announced the decrease of the GST from 7% to 6%, and subsequently to 5% over the next five years.