Why Dark Money Is Legal: The Complete Mechanics

In the 2024 federal election cycle, $1.9 billion in dark money was spent on American elections — a new record, according to the Brennan Center for Justice. That figure represents money whose original donors are legally invisible to voters, to journalists, and in most cases to regulators.

The term "dark money" is often used loosely. This article uses it precisely: money spent to influence elections whose original source is not publicly disclosed under federal law. The system that enables this is not a single loophole. It is a set of interlocking legal structures — tax code provisions, campaign finance thresholds, disclosure timing rules, and enforcement gaps — that together create a legal architecture for anonymous political spending at scale.

Understanding how dark money works requires understanding four systems: the tax code foundation, the disclosure trigger system, the foreign money pathway, and the current state of reform. Each operates independently. Together, they produce the $1.9 billion figure.

Part I: The Tax Code Foundation

The legal foundation of dark money is Section 501(c)(4) of the Internal Revenue Code. This provision grants tax-exempt status to organizations "operated exclusively for the promotion of social welfare." The critical word is "exclusively" — and the critical fact is that the IRS does not interpret it to mean what it says.

In 1959, the IRS issued a regulatory interpretation (26 CFR § 1.501(c)(4)-1) that reinterpreted "exclusively" to mean "primarily." Under this reading, a 501(c)(4) organization can engage in political activity — including funding campaign advertising — as long as political spending does not constitute the "primary" purpose of the organization. The IRS has adopted a de facto standard that political activity can constitute up to 49.9% of total expenditures while still qualifying as "primarily" social welfare.

This single regulatory interpretation — never enacted by Congress, never tested at the Supreme Court — is the foundation on which the entire dark money system rests.

The tax code created the entities. The chain shows how the money moves through them.

The Chain

The interaction between these three entity types creates a specific financial pathway. An anonymous donor contributes to a 501(c)(3) public charity and receives a tax deduction. The 501(c)(3) makes a grant to a 501(c)(4) social welfare organization. The 501(c)(4) transfers funds to a super PAC. The super PAC buys election advertising.

At each step, donor identity is erased. The 501(c)(3) collects donor names on IRS Schedule B, but that schedule is redacted from publicly available Form 990 returns. The 501(c)(4) has no public donor disclosure requirement at all. The super PAC discloses all its donors — but its donor is the 501(c)(4), not the individuals who funded it.

At a 2023 House Ways and Means Committee hearing, nonprofit tax law professor Philip Hackney confirmed the chain directly: a foreign national can donate to a 501(c)(3), which passes money to a 501(c)(4), which donates to a super PAC running television advertising. At no point is the foreign national's identity publicly disclosed.

The Enforcement Collapse

The IRS is the agency responsible for enforcing the political activity limits on 501(c)(4) organizations. It has effectively stopped doing so.

Since 2015, the IRS has not stripped a single 501(c)(4) of its tax-exempt status for violating political activity rules, according to ProPublica. The IRS Exempt Organizations division shrank from 942 staffers in 2010 to 585 in 2018 — a 38% reduction in enforcement capacity during a period when the number of politically active nonprofits was growing rapidly.

The proximate cause was the 2013 IRS scandal, in which the agency was found to have applied heightened scrutiny to conservative nonprofits seeking tax-exempt status. Later reporting confirmed that progressive groups were also targeted. The political fallout was severe: congressional budget cuts, institutional paralysis, and a lasting reluctance to scrutinize any nonprofit's political activity. The Campaign Legal Center described the result as "de facto enforcement paralysis."

The Pop-Up Model

The Arabella Advisors network — now operating as Sunflower Services — refined a fiscal sponsorship model that adds another layer of opacity. Under this model, named political campaigns operate as "projects" under an existing 501(c)(4) umbrella organization like the Sixteen Thirty Fund. These "pop-up" groups have their own names, their own websites, their own messaging — but they are not separate legal entities. They file no independent IRS disclosures. They appear and disappear as political needs dictate.

OpenSecrets has documented that the Sixteen Thirty Fund and its 501(c)(3) partner, the New Venture Fund, have fiscally sponsored dozens of such groups. As political financing expert Scott Walter testified before the House Ways and Means Committee in December 2023: "Nothing in the 990 requires them to say anything about those particular groups, which lets those groups hide in greater darkness than a regular nonprofit."

"Nothing in the 990 requires them to say anything about those particular groups, which lets those groups hide in greater darkness than a regular nonprofit."

The tax code built the vehicles. The disclosure system determines what the public is allowed to see.

Part II: The Disclosure Trigger System

The Federal Election Campaign Act sets different disclosure standards depending on the type of political communication and its proximity to an election. Understanding what triggers disclosure — and what does not — is essential to understanding how dark money operates in practice.

The $200 Donor Identification Threshold

Political committees — PACs, candidate committees, party committees — must disclose the identity, address, occupation, and employer of any contributor giving more than $200 in a calendar year. The catch: this requirement applies only to registered political committees. 501(c)(4) organizations are not political committees and are not covered by this rule.

The $10,000 Electioneering Communication Threshold

Any entity spending more than $10,000 on "electioneering communications" must file a disclosure with the FEC within 48 hours. Electioneering communications are defined as broadcast ads that name a federal candidate within 60 days of a general election or 30 days of a primary. The catch: ads that run outside these timing windows are not classified as electioneering communications — regardless of their content or intent.

The $1,000 Final 20-Day Threshold

An independent expenditure of $1,000 or more within the final 20 days of an election must be reported to the FEC within 24 hours. The catch: "independent expenditure" requires "expressly advocating" for or against a candidate — which under the Buckley v. Valeo "magic words" test means using explicit language such as "vote for," "vote against," "elect," or "defeat."

The Magic Words Doctrine

In 1976, the Supreme Court's decision in Buckley v. Valeo (424 U.S. 1) established the "magic words" test. The Court held that only communications containing explicit words of advocacy — "vote for," "vote against," "elect," "support," "oppose," "defeat," "reject" — could be regulated as campaign contributions or expenditures under FECA.

The practical consequence is that 501(c) groups routinely buy television and radio airtime, produce candidate-focused advertising, and report zero political spending to the FEC — because their ads carefully avoid the magic words and air outside the timing windows. As OpenSecrets has documented, this is not an edge case. It is the standard operating model for dark money organizations.

The Donor Disclosure Loophole

Even when the $10,000 electioneering communication threshold is triggered, there is a second layer of opacity on the donor side.

FECA requires organizations filing electioneering communication disclosures to identify donors who contributed at least $1,000. But there is an exception: if the organization establishes a separate bank account specifically for electioneering communications, only donors to that account must be disclosed — not the organization's general donors.

The FEC's own Republican commissioners issued a policy statement in 2022 clarifying that a donation is only "earmarked for political purposes" if it is "designated or solicited for, or restricted to, activities or communications that expressly advocate the election or defeat of a clearly identified candidate." A donor who gives $10 million to a 501(c)(4) with a general mission — without earmarking for a specific ad — is not reportable under this interpretation, even if that $10 million funds an ad campaign the day before an election.

Domestic dark money has a legal architecture. Foreign money has an even simpler path.

Part III: FARA and Foreign Money

The Foreign Agents Registration Act was enacted in 1938 to counter Nazi propaganda operations in the United States. It requires any person acting as an agent of a "foreign principal" — a foreign government, political party, foreign organization, or non-U.S. person outside the country — to register with the Department of Justice and publicly disclose the relationship, activities, and financial transactions.

FARA's structural gap is that it regulates agents acting on behalf of foreign principals — not the financial instruments through which foreign money moves into the U.S. political system. A foreign billionaire who writes a check to a U.S. 501(c)(3) public charity requires no FARA registration because the foreign donor is not acting as an "agent" — they are simply donating.

Federal law (52 U.S.C. §30121) prohibits foreign nationals from donating to campaigns, super PACs, or party committees. But this prohibition does not extend to 501(c)(3) or 501(c)(4) nonprofits. The result is a legal pathway through which foreign money can enter the U.S. political system without triggering either FARA registration or FECA disclosure.

The Ballot Measure Gap

In 2018, the Australian mining company Sandfire Resources spent nearly $288,000 to defeat Montana's I-186 ballot initiative on mining regulations. In 2021, the FEC dismissed a complaint about the spending, concluding that federal campaign finance law's prohibition on foreign contributions "does not apply to spending on ballot measures, referenda or even recall elections."

The FEC's Democratic chair at the time wrote that she urged Congress to close the loophole but the commission was "bound by the law as it currently stands." Swiss billionaire Hansjörg Wyss has donated more than $245 million to the Sixteen Thirty Fund and New Venture Fund since 2016 — organizations that have been active in ballot measure campaigns and political advocacy.

FARA Enforcement

FARA enforcement has become significantly more active since 2017. In 2024 alone, the DOJ pursued high-profile cases: charges against former Rep. Henry Cuellar for allegedly advancing Azerbaijani interests, former New York state official Linda Sun for allegedly acting as an undisclosed Chinese agent, and the conviction of former Senator Robert Menendez for acting as an agent of Egypt.

In February 2026, Yaoning "Mike" Sun was sentenced to four years in prison for acting as an illegal agent of the Chinese government while working as a campaign advisor for a Southern California politician. The DOJ conducted 26 FARA inspections in 2024 — the most since 1977.

But FARA prosecutions overwhelmingly involve people acting as undisclosed agents — lobbyists, consultants, government officials — not foreign nationals who simply donate money to U.S. nonprofits. The financial pathway remains open.

The system is documented. The question is whether anyone is trying to change it.

Part IV: The State of Reform

Multiple reform proposals have been introduced at the federal and state level. None has closed the core structural gaps.

What Reform Has Not Addressed

No currently active legislation addresses the digital advertising gap. Online ads from 501(c)(4) organizations that avoid magic words and run outside timing windows generate zero FEC disclosure at any dollar amount. The Stand By Every Ad Act — which would require ads to display links to top donors — has been proposed but not advanced.

No IRS movement toward redefining "primarily" for 501(c)(4) political activity has occurred. The 1959 regulatory interpretation that converted "exclusively" to "primarily" remains in force, unchallenged and unchanged.

Reading the Filings

For anyone trying to follow the money in 2026 — journalists, researchers, voters — the practical question is: what do the available filings actually tell you?

The System

Dark money is not a bug in American campaign finance law. It is the predictable output of a system in which tax-exempt status permits political spending, disclosure rules contain structural timing and language gaps, enforcement has collapsed, and foreign money can enter through nonprofit channels that neither FARA nor FECA covers.

The $1.9 billion spent in 2024 was not spent illegally. It was spent through legal channels that were designed — or have evolved — to permit exactly this kind of anonymous, large-scale political spending. Understanding the mechanics is the first step toward evaluating whether the system should change.

"There are new loopholes being exploited every day."

Sources: Brennan Center for Justice (2025); ProPublica (2020, updated 2025); OpenSecrets; Congress.gov; CRS IF11398; FEC.gov; Campaign Legal Center; House Ways and Means Committee (December 2023, May 2024); Buckley v. Valeo, 424 U.S. 1 (1976); 52 U.S.C. §§ 30104, 30121; 22 U.S.C. § 611 (FARA); 26 CFR § 1.501(c)(4)-1; Inside Political Law; Federal Register (AG Order No. 6121-2024); Wesleyan Media Project; TRAC at Syracuse University.