Here is information about supply-side economics.
Supply-side economics is a macroeconomic theory that postulates economic growth can be most effectively fostered by lowering taxes, decreasing regulation, and allowing free trade. According to supply-side economics, consumers will benefit from greater supplies of goods and services at lower prices, and employment will increase.
The last major implementation of supply-side economics was the Tax Cuts and Jobs Act of 2017 (TCJA).
Major elements of the changes include reducing tax rates for businesses and individuals, increasing the standard deduction and family tax credits, eliminating personal exemptions and making it less beneficial to itemize deductions, limiting deductions for state and local income taxes and property taxes, further limiting the mortgage interest deduction, reducing the alternative minimum tax for individuals and eliminating it for corporations, reducing the number of estates impacted by the estate tax, and cancelling the penalty enforcing individual mandate of the Affordable Care Act (ACA).
The result of this was an immediate increase in the Federal Deficit as Percent of Gross Domestic Product.
The unemployment rate continued to decline as it had since the end of the 2009 recession. The slope of the line did not increase between 2017 and 2020 so the TCJA did not improve the unemployment rate.
Real Gross Domestic Product continued to increase as it had since the end of the 2009 recession. The slope of the line did not increase between 2017 and 2020 so the TCJA did not improve the rate of increase of real GDP.
At this point in the cycle, the main impacts on the deficit are the pandemic-related spending items, not the TCJA. Middle-class tax decreases from the TCJA are scheduled to end in 2022 but the corporate tax breaks will remain.
The main results of the TCJA have been increased government deficits and increased income inequality. There were no impacts on GDP growth or unemployment.