What are 501(c)(4)s?
Section 501(c)(4) social welfare groups get their exemption for being "primarily engaged in promoting in some way the common good and general welfare of the people of the community."34 This is a very broad definition, and it covers a wide variety of organizations: the American Civil Liberties Union and the American Association of Retired People are both 501(c)(4)s, as is the National Rifle Association. In addition to the few nationally known organizations there are tens of thousands of smaller ones, such as Rotary Clubs, volunteer fire departments, and neighborhood associations.
Like other 501(c)s, social welfare groups are supposed to devote most of their time, money, and other resources to their primary activities—the ones that got them a tax exemption. Thanks to the
IRS's vague definition of "social welfare," 50i(c)(4)s are easier to form than other politically active 50i(c)s: 501(c)(5) labor unions and 501(c)(6) business associations serve well-defined communities of beneficiaries, but a 501(c)(4) can claim to be providing some kind of social benefit to the entire country. Just how easy it was to form 50i(c)(4)s became clear when Citizens United made them even bigger conduits for outside money than they had been in 2008.