501(c)(4)

A 501(c) organization, or simply a 501(c), is a tax-exempt nonprofit organization in the United States. Section 501(c) of the United States Internal Revenue Code (26 U.S.C. § 501) provides that 29 types of nonprofit organizations are exempt from some federal income taxes. Sections 503 through 505 set out the requirements for attaining such exemptions. Many states refer to Section 501(c) for definitions of organizations exempt from state taxation as well. 501(c) organizations can receive unlimited contributions from individuals, corporations, and unions.

The most common type of US tax-exempt nonprofit organization falls under category 501(c)(3), whereby a nonprofit organization is exempt from federal income tax if its activities have the following purposes: charitable, religious, educational, scientific, literary, testing for public safety, fostering amateur sports competition, or preventing cruelty to children or animals.

According to the IRS Publication 557, in the Organization Reference Chart section, the following is an exact list of 501(c) organization types and their corresponding descriptions.

Under Section 511, a 501(c) organization is subject to tax on its "unrelated business income", whether or not the organization actually makes a profit, but not including selling donated merchandise or other business or trade carried on by volunteers, or certain bingo games. Disposal of donated goods valued over $2,500, or acceptance of goods worth over $5,000 may also trigger special filing and record-keeping requirements.

Tax exemption does not excuse an organization from maintaining proper records and filing any required annual or special-purpose tax returns, e.g., 26 U.S.C. § 6033 and 26 U.S.C. § 6050L. Prior to 2008, an annual return was not generally required from an exempt organization accruing less than $25,000 in gross income yearly. Since 2008, most organizations whose annual gross receipts are less than $50,000 must file an annual information return known as Form 990-N. Form 990-N must be submitted electronically using an authorized IRS e-file provider. Form 990, Form 990-EZ, and Form 990-PF may be filed either by mail or electronically through an authorized e-file provider.

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