免稅[1]是指個人或機構在某種情況下可以不用向政府繳納稅收。例如某些慈善組織可以不用向政府繳納財產稅和所得稅，某些地區的人在購買商品後途徑海關時不用繳納關稅。有時候某些機構、公司和組織只會被免除部分種類的稅，但是其他的種類的稅依然要交，例如美國某些組織可以不用繳納聯邦所得稅， [2] 但是各種消費稅依然要繳納。 [3]
As an example, UK charities law （頁面存檔備份，存於網際網路檔案館） defines the types of organizations which may qualify as registered charities, and places limits on their actions. 26 USC 501(a). The exemption from Federal income tax is longstanding. This exemption formed part of the Revenue Act of 1894. The 1894 Act was the first broadly applicable U.S. tax on corporate income, but was soon declared unconstitutional. Since ratification of the Sixteenth Amendment to the United States Constitution in 1913, the exemption for charitable, religious, and educational organizations has been included in all subsequent Federal income tax law. See Belknap, Chauncey, "The Federal Income Tax Exemption of Charitable Organizations: Its History and Underlying Policy," 1954, reprinted (very large file) as pages 2025-2043 of the Research Papers of the Commission on Private Philanthropy and Public Needs, Volume IV, 1977. 26 USC Subtitle D （頁面存檔備份，存於網際網路檔案館） excise taxes are imposed on particular goods or services, generally without exemptions. Certain of these taxes apply primarily to tax-exempt organizations. See, e.g., 26 USC 4911, tax on excess expenditures to influence legislation. 26 USC 3101 and 3301 generally impose social security and unemployment taxes on all organizations. Note that income from certain types of services, such as services as a minister, may be exempt from the definition of income for these taxes. Employees of certain nonprofit and governmental organizations are eligible to participate in different sorts of deferred compensation plans than employees of other organizations. Compare 26 USC 401, IRS Publication 560 （頁面存檔備份，存於網際網路檔案館） and others vs. 26 USC 403(b), IRS Publication 571 （頁面存檔備份，存於網際網路檔案館）.
