The revenue loss from tax expenditures is enormous: Discretionary spending, noninterest mandatory spending, total revenue, and tax expenditures as a share of GDP, 2017

 Discretionary spending 6.3%
 Mandatory spending minus net interest 13.1%
 Total revenue 17.3%
 Tax expenditures 7.7%

Source: EPI analysis of data from the Government Accountability Office (GAO 2019) and the Congressional Budget Office (CBO various years)

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