A 501(c)(3) organization is a United States corporation, trust, unincorporated association or other type of organization exempt from federal income tax under section 501(c)(3) of Title 26 of the United States Code. It is one of the 29 types of 501(c) nonprofit organizations in the US.

501(c)(3) tax-exemptions apply to entities that are organized and operated exclusively for religious, charitable, scientific, literary or educational purposes, for testing for public safety, to foster national or international amateur sports competition, or for the prevention of cruelty to children or animals. 501(c)(3) exemption applies also for any non-incorporated community chest, fund, cooperating association or foundation organized and operated exclusively for those purposes. There are also supporting organizations—often referred to in shorthand form as "Friends of" organizations.

26 U.S.C. § 170 provides a deduction for federal income tax purposes, for some donors who make charitable contributions to most types of 501(c)(3) organizations, among others. Regulations specify which such deductions must be verifiable to be allowed (e.g., receipts for donations of $250 or more).

Due to the tax deductions associated with donations, loss of 501(c)(3) status can be highly challenging if not fatal to a charity's continued operation, as many foundations and corporate matching funds do not grant funds to a charity without such status, and individual donors often do not donate to such a charity due to the unavailability of tax deduction for contributions.