本文主要探討美國內地稅法Internal Revenue Code（I.R.C.）§501（c）（3）非營利組織課稅制度。I.R.C. §501（c）組織設立宗旨為致力於有益公共福利，而非以營業牟利為目的，因此一般多以「非營利組織」稱之。非營利組織自美國建國以來即伴隨著美國的歴史成長。根據「都市協會慈善統計國家中心」（Urban Institute, National Center for Charitable Statistics）統計資料顯示，在二○一○年美國的非營利組織共計有一百五十一萬四千五百三十家，由此可見，非營利組織所提供的有益公共福利已成為美國民眾日常生活中的一部分，深深的融入美國社會。美國政府對於非營利組織亦給予眾多優惠，例如：聯邦所得稅減免、郵資折扣、得發行免稅債券等不同的優惠。並且為鼓勵社會大眾及企業對非營利組織捐贈，內地稅法亦規定對非營利組織捐贈之納稅義務人給予所得稅、遺產稅、贈與稅等扣除額優惠。雖然內地稅法給予非營利組織稅捐減免優惠，但同時也規範非營利組織符合稅捐減免優惠之資格。換言之，若非營利組織違反內地稅法稅捐減免優惠條件，其稅捐減免優惠身分將被取消。本文將探討非營利組織稅捐減免優惠要件之規定，且一併討論說明非營利組織從事與其設立目的無關的商業活動所產生的所得之規定。

This article examines tax rules governing I.R.C. §501(c)(3) nonprofit organizations in the United States. Nonprofit organizations are defined in the Internal Revenue Code ("I.R.C.") under section 501(c). Because section 501(c) organizations are organized and pursued public benefit purposes, they are known as "nonprofit organizations". According to the Urban Institute's National Center for Charitable Statistics, there were as many as 1.5 million nonprofit organizations registered and operated in 2010. Nonprofit organizations are a crucial part of society, providing benefits to the public. Nonprofit organizations receive tax exemptions and other benefits including reduced postal rates, issuance of tax-exempt bonds, etc. Taxpayers who donate to nonprofit organizations are able to deduct their contributions on their tax returns. Even though, a nonprofit organization enjoys numerous benefits, it will lose its tax-exempt status for not complying with I.R.C. requirements and restrictions. This article examines and discusses the requirements and restrictions that are placed on I.R.C. §501(c)(3) nonprofit organizations. In addition, this article will also discuss unrelated business income tax.