and Estate taxes were imposed on the transferor rather than the recipient. Many states adopted either inheritance taxes or estate and gift taxes, often computed as the amount allowed as a deduction for federal purposes. These taxes remained under 1% of government revenues through the 1990s. All governments within the United States provide tax exemption for some income, property, or persons. These exemptions have their roots both in tax theory, federal and state legislative history, and the United States Constitution. See also History of taxation in the United States Internal Revenue Service List of countries by tax rates List of countries by tax revenue as percentage of GDP Tariffs in United States history Tax Cuts and Jobs Act of 2017 Tax resistance in the United States Stepped-up basis References Further reading Government sources: IRS Publication 17, Your Federal Income Tax U.S. Customs and Border Protection booklet Importing into the United States IRS website Links to state websites Customs and Border Patrol website Alcohol and Tobacco Tax website Law & regulations: Federal tax law, 26 USC Code of Federal Regulations, 26 CFR Standard texts (most updated annually): Fox, Stephen C., Income Tax in the USA, 2013 edition Hoffman, William H. Jr.; et al., South-Western Federal Taxation, 2013 edition Pratt, James W.; Kulsrud, William N.; et al, Federal Taxation, 2013 edition (cited above as Pratt). Whittenberg, Gerald; Altus-Buller, Martha; and Gill, Stephen, Income Tax Fundamentals 2013, Hellerstein, Jerome R., and Hellerstein, Walter, State and Local Taxation: Cases and Materials, 2005, Reference works: CCH U.S. Master Tax Guide, 2010 RIA Federal Tax Handbook 2010 Popular publications (annual): J.K. Lasser's Your Income Tax for 2010 External links Tariffs applied by the United States as provided by ITC's Market Access Map, an online database of customs tariffs and market requirements. Tax policy of the United States