A massive trove of tax information obtained by ProPublica, covering thousands of America’s wealthiest individuals, reveals what’s inside the billionaires’ bag of tricks for minimizing their personal tax bills — sometimes to nothing.

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Today, ProPublica is launching the first in a series of stories based on the private tax data of some of our nation’s richest citizens. We obtained the information from an anonymous source who provided us with large amounts of information on the ultrawealthy, everything from the taxes they paid to the income they reported to the profits from their stock trades.

In the coming months, we plan to use this material to explore how the nation’s wealthiest people — roughly the .001% — exploit the structure of our tax code to avoid the tax burdens borne by ordinary citizens.

Many will ask about the ethics of publishing such private data. We are doing so — quite selectively and carefully — because we believe it serves the public interest in fundamental ways, allowing readers to see patterns that were until now hidden.

Tax experts have long understood that the wealthiest Americans reap outsized benefits from the federal tax code’s emphasis on taxing income rather than assets like stock holdings and property. Yet, when The New York Times disclosed in 2020 that President Donald Trump had amassed so many deductions he paid no taxes in 11 of 18 years, it was assumed that his case was an anomaly, reflecting the unique breaks real estate developers receive under our tax system.

It is now clear that there isn’t just one such taxpayer — there are many, in multiple industries. We believe that disclosing the identities of billionaires who paid little to no taxes in years their fortunes grew by billions of dollars will help readers understand the magnitude of the tax advantages the ultrarich enjoy.

We also believe that disclosure of specific figures about the tax returns of people like Jeff Bezos, Michael Bloomberg, Warren Buffett and Elon Musk will deepen readers’ interest and understanding of this complex and arcane subject.

Our publication of this tax data comes at a possibly pivotal moment in America’s long, often contentious debate about the fairness of our tax system. The Biden administration has proposed raising a number of taxes to pay for additional trillions of dollars in government spending. So far, the conversation in Washington has been dominated by an issue long seen as central on Capitol Hill: whether to increase the top tax rate from its current level of 37% by a few percentage points. Such a change, as our story shows, would touch the richest hardly at all.

The secret tax files offer new, factual evidence for lawmakers considering such changes: Should the biggest winners in America’s epochal concentration of wealth over the last 40 years be permitted to pay levies of considerably less than 37%?

A second question certain to arise is the motives and identity of the source who has provided this data to ProPublica. We live in an age in which people with access to information can copy it with the click of a mouse and transmit it in a variety of ways to news organizations. Many years ago, ProPublica and other news organizations set up secure systems that allow whistleblowers to transmit information to us without revealing their identity.

We do not know the identity of our source. We did not solicit the information they sent us. The source says they were motivated by our previous coverage of issues surrounding the IRS and tax enforcement, but we do not know for certain that is true. We have considered the possibility that information we have received could have come from a state actor hostile to American interests. In particular, a number of government agencies were compromised last year by what the U.S. has said were Russian hackers who exploited vulnerabilities in software sold by SolarWinds, a Texas-based information technology company. We do note, however, that the Treasury Department’s inspector general for tax administration wrote in December that, “At this time, there is no evidence that any taxpayer information was exposed” in the SolarWinds hack.

While the revelations in today’s story are extraordinary, the procedures we used in assessing the data’s value are standard in the craft of journalism. When a reporter makes contact with a source and is provided information, we begin with questions. Is the material authentic? Is it newsworthy? Is it complete?

We understand that nearly everyone who provides material to a reporter is doing so in ways that reflect their worldview, agenda or biases. We have long held that those motives are irrelevant if the information is reliable.

Seven years ago, a team of hackers believed to be directed by the North Korean government revealed a trove of emails to and from Sony. The motivation, American intelligence officials said at the time, was to punish the studio for having distributed a satirical movie about Kim Jong Un, the leader of North Korea. Some of the documents released through that breach led to a 2015 ProPublica story on questionable political contributions in Los Angeles. We published that story because it was important and something we believed the public needed to know. We publish today’s much more important story for similar reasons.

Provenance is not essential; accuracy is. We have gone to considerable lengths to confirm that the information sent to us is accurate. We compared the tax data in our possession to other sources of the same information wherever we could find them, some of which were public (a tax return for a candidate for national office), others of which were private. In every instance we were able to check — involving tax filings by more than 50 separate people — the details provided to ProPublica matched the information from other sources.

Having said that, because it remains possible that not everything in our database is accurate, every person whose tax information was described in today’s story was given an opportunity to point out inaccuracies or omissions before the story appeared.

There is also a legal question here, and we want you to know we have taken it seriously. A federal law ostensibly makes it a criminal offense to disclose tax return information. But we do not believe that law would be constitutional if applied to bar or sanction publication of a story in the public interest when the news organization did not itself remove the information from the control of the IRS or solicit anyone else to do so — as we did not. And this is not our first experience with this law.

In 2012, someone at the IRS (we don’t know who or why; they used a plain brown IRS envelope) sent ProPublica copies of tax filings seeking exemption for a number of political committees, including Republican political guru Karl Rove’s Crossroads GPS. The filings were not yet supposed to be public, and the IRS indicated that it would consider our publication of them to be criminal. We explained our view of the constitutionality of that statute as applied in such circumstances and published our story, which raised concerns about whether Rove’s group had been forthcoming with the agency. We never heard about the matter from the IRS again.

Finally, it’s worth noting that taxes have not always been a private matter. Many politicians, including every presidential nominee for decades, except Trump, has made his or her tax returns public.

Today, in Wisconsin, anyone can file a public records request to find out how much state residents pay in state taxes. Outside of the U.S., Sweden, Norway and Finland make public every citizen’s tax returns.

We hope you will read today’s story and the following stories in the series, and perhaps participate in the public debate about the future of our tax system. We welcome any help, confidential or otherwise, to further our reporting. If you think you have something to contribute, you can use this page.