A 501(c)(4) is a federal tax-exempt category for nonprofits organized for the "promotion of social welfare." These groups can spend on policy advocacy and legislative lobbying without limit, can engage in political campaign activity as long as it isn't their "primary" purpose, and don't disclose donor identities to the public.
The Internal Revenue Service interprets "primary purpose" loosely — many groups spend close to half their budget on election ads while still qualifying. The Rockbridge Network, Americans for Prosperity, and dozens of single-cycle pop-up groups have used 501(c)(4) status to run election-season ads with anonymous funding.
The IRS rarely revokes 501(c)(4) status for excessive political activity, and the FEC treats issue ads that don't expressly say "vote for/against" as outside its reporting jurisdiction. Together those gaps let 501(c)(4)s serve as the standard dark money vehicle.
Anonymous money buying political ads is the largest category of campaign spending Americans can't trace. When you can't see who paid for the message, you can't weigh the messenger's interest against the claim.
People often think 501(c)(4)s are barred from political ads. In practice, they can run political ads as long as election work isn't their "primary" activity — a standard the IRS rarely enforces.
Anonymous money buying political ads is the largest category of campaign spending Americans can't trace. When you can't see who paid for the message, you can't weigh the messenger's interest against the claim.
People often think 501(c)(4)s are barred from political ads. In practice, they can run political ads as long as election work isn't their "primary" activity — a standard the IRS rarely enforces.