MONEYINPOLITICS.wtf
America’s most comprehensive dictionary of campaign finance jargon
501(c)(4)
noun1 a shorthand reference for groups that claim freedom from U.S. taxes under Section 501(c)(4) of the Internal Revenue Code; also known as social welfare organizations or a political advocacy organization; political activity cannot be the primary purpose the group, but some participation is allowed; sometimes used to shield the identity of donors from public scrutiny
The best-known of these groups is the Tea Party-supporting Americans for Prosperity, a 501(c)(4) group cofounded by billionaire David Koch, who with his brother Charles is credited with pioneering some of the bolder new campaign fundraising tactics.— ProPublica
A Super PAC may receive unlimited contributions from an outside 501(c)(4) or a transfer from an affiliated (c)(4).— The Sunlight Foundation