Dark money is money spent to influence elections where the public never learns who originally supplied it. It usually moves through nonprofits, such as 501(c)(4) “social welfare” groups and 501(c)(6) trade associations, that don’t have to publicly name their donors. Sometimes those nonprofits, or LLCs set up for the purpose, give to super PACs, so the super PAC’s federal filing shows only the middleman. All of this is legal under current US law.
You’ll see the results in every competitive race this fall: ads from groups with generic names that you can’t trace to a person or company. Here’s how the system works, where it came from, and what you can actually find out.
How does dark money work? #
Political money in the US moves through a handful of legal structures, and each has different rules about limits, disclosure and coordination.
| Entity | Can take unlimited money? | Must publicly disclose donors? | Can coordinate with a campaign? |
|---|---|---|---|
| Candidate committee | No, federal limits apply | Yes, to the FEC | It is the campaign |
| Traditional PAC | No, limits apply | Yes | Can give to candidates within limits |
| Super PAC | Yes | Yes, but donors can be other groups | No |
| 501(c)(4) social welfare group | Yes | Generally no | No, for independent spending |
| 501(c)(6) trade association | Yes | Generally no | No, for independent spending |
The table shows where the gap is. A super PAC must list its donors, but if a donor is a 501(c)(4) that doesn’t disclose its own funders, the trail stops there. The same thing happens when an LLC with no public owners writes the check.
The rule that keeps 501(c)(4)s in politics #
A 501(c)(4) exists, on paper, to promote social welfare. It can do political campaign work as long as politics isn’t its “primary purpose.” In practice many groups treat that as permission to spend just under half of their budget on election activity, and they count issue advocacy, which is broadly defined, as non-political.
A 2018 federal court ruling (CREW v. FEC) narrowed one gap. Groups that make independent expenditures must now report donors who gave above the threshold for the purpose of furthering those expenditures. Donors who give for “general support” can still stay anonymous.
Issue ads versus express advocacy #
Federal disclosure rules turn on whether an ad expressly tells you how to vote. The Supreme Court’s 1976 Buckley v. Valeo decision gave rise to the “magic words” test: “vote for,” “elect,” “defeat” and similar phrases. An ad that says “Senator Smith voted to raise your taxes. Call Smith and tell her to stop” never uses them. It’s treated as an issue ad, even though its purpose is plain, and it carries lighter reporting requirements.
Where did dark money come from? #
Two 2010 court decisions opened the door. In Citizens United v. FEC, the Supreme Court ruled that corporations and unions can spend unlimited amounts on independent political speech. Months later, SpeechNow.org v. FEC led to super PACs, which can raise unlimited sums as long as they don’t coordinate with candidates. The Court assumed disclosure would keep the new spending accountable, but tax law still let nonprofits keep their donors private.
The Sunlight Foundation popularized the term “dark money” during the 2010 midterms. Spending grew fast. By OpenSecrets’ tracking, reported dark money went from under $5.2 million in 2006 to more than $300 million in 2012 and over $1 billion in 2020.
It isn’t a one-party tool. OpenSecrets found that most 2012 dark money backed conservative causes, while in 2020 more of it flowed to groups aligned with Democrats. Both parties’ donor networks now use the same structures. You can browse the numbers on OpenSecrets’ dark money pages.
Why do donors use dark money? #
Two reasons come up again and again.
- Size. Direct gifts to candidates are capped. A nonprofit can accept a single eight-figure check.
- Privacy. Some donors fear boycotts, harassment or blowback at work. Others simply don’t want their name next to an attack ad.
Anonymity also changes the ads themselves. Candidates tend to keep their own ads positive because their name is on them. Outside groups with no public donors carry less reputational risk, so a lot of the harshest ads in a race come from them.
How to trace who paid for a political ad #
You often can’t find the original donor, but you can get closer than most people think.
- Read the disclaimer. Federal law requires a “paid for by” line on TV, radio, mail and most paid online ads. That tells you the sponsoring group.
- Search the group on FEC.gov. Super PACs and PACs list donors; nonprofits that make independent expenditures file reports too.
- Check the IRS Tax Exempt Organization Search. A nonprofit’s Form 990 shows revenue, spending and officers, even though donor names are withheld from the public copy.
- Look up online ads. The Meta Ad Library and Google Ads Transparency Center show who ran political ads, roughly how much they spent and where.
- Check TV buys. Broadcasters post political ad contracts in the FCC’s public inspection files.
- Try your state’s disclosure site. Several states require more than federal law does, especially for state races.
Can dark money move the polls? #
Heavy ad spending can move a race at the margins, especially when one side has the airwaves to itself. But most competitive races have saturation spending from both sides, and the effect of any single wave of ads is hard to isolate.
The practical way to judge it is to watch a race’s polling average over time rather than reacting to one survey. Election Tracker gives every Senate and governor race with polling a 30-day average, plus a trend line once there’s enough data. If a late ad blitz shifts a race, you’ll see it across several pollsters in that line. One poll moving could just be noise. Every poll card also lists the pollster, sample size, population and field dates, so you can check whether the movement started before or after the ads did.
Efforts to change the rules #
Federal reform has stalled for years, while some states have moved on their own.
- The DISCLOSE Act. Repeatedly introduced by Senate Democrats, it would require groups spending in elections to disclose donors who give $10,000 or more. It hasn’t passed; opponents argue donor disclosure chills free association.
- Court limits on disclosure. In Americans for Prosperity Foundation v. Bonta (2021), the Supreme Court struck down California’s rule that charities hand their major donor lists to the state attorney general.
- IRS reporting. A 2020 Treasury rule ended the requirement that most tax-exempt groups other than charities list donor names and addresses for the IRS, though they must keep the records.
- State measures. Arizona voters approved Proposition 211 in 2022, requiring disclosure of the original sources of large campaign contributions; it has been challenged in court. California requires top funders to appear on many political ads.
- FEC enforcement. The Federal Election Commission needs four of its six commissioners to act. It lost that quorum on May 1, 2025, and without one it can’t open enforcement cases or write new rules. Check the FEC’s site for its current status.
For the donor side of the system, see our guide to PACs versus super PACs and how to track campaign donations with FEC data.
Frequently asked questions #
Is dark money legal? #
Yes. Nonprofits such as 501(c)(4)s and 501(c)(6)s can raise unlimited money and spend part of it on politics without publicly naming donors, as long as politics isn’t their primary purpose and they don’t coordinate with campaigns. Lying on required reports or funneling money through a straw donor is illegal.
What’s the difference between a super PAC and a dark money group? #
Disclosure. A super PAC can raise and spend unlimited sums but must report its donors to the FEC. A dark money nonprofit can also spend freely but generally doesn’t disclose its donors. When a nonprofit gives to a super PAC, the super PAC’s report names the nonprofit and the trail ends.
Does dark money favor one party? #
Not consistently. OpenSecrets data shows the balance has swung between cycles: conservative groups dominated in 2012, while in 2020 more dark money went to Democratic-aligned groups. Both sides’ donors now use the same legal structures.
How does dark money affect polling? #
Indirectly, through advertising. Big ad campaigns can shift a candidate’s favorability and vote share, usually by a point or two rather than dramatically. Watching a race’s average over several weeks is the best way to see whether spending is actually moving voters. Our explainer on who pays for political polls covers the related question of who funds the surveys themselves.
Can I find out who funds a specific nonprofit? #
Sometimes. Donors occasionally disclose voluntarily, and investigative reporters piece together funding from tax filings of the donors’ own foundations. The nonprofit’s Form 990 won’t list donor names publicly, but it shows how much it raised and what it spent, which is often enough to see how big a player it is.