Main Street Millionaires: What 11 Million Tax Records Show

Owen Zidar and Eric Zwick used U.S. Treasury and IRS data to study who is a millionaire in America, work that became the book "The Everywhere Millionaire: Who Is Really Rich in America and How They Got There." The book was set for release on September 15, 2026. CBS News Princeton Economics

Zidar is with Princeton University. With Zwick, he built the first de-identified database that links business tax records to owners and workers. De-identified means names and personal details are removed. The linkage is administrative, not survey based. The unit is the firm-owner link, one business matched to one owner at a time. Princeton Economics

The book describes where Main Street millionaires come from, how they grew rich, and how much money they make. It focuses on owners of closely held businesses, meaning private firms with a small number of owners. That is different from public-company pay or inherited portfolios.

That framing builds on earlier joint work. NBER Working Paper w25442 is titled "Capitalists in the Twenty-First Century." It used tax data linking 11 million firms to their owners. It finds that top pass-through profit, which is business profit taxed on the owner's own return, goes to working-age owners of closely held, mid-market firms. NBER Wojciech Kopczuk and Eric Zwick authored "Business Incomes at the Top."

Zidar and Zwick also wrote a Chicago Booth Review article titled "Inside the Lives of the Main Street Millionaires." It looks at wealth for business owners in the top 1 percent, the highest-earning one in a hundred households. The focus is owners found in the tax data, with income tied to operating firms.

Publication brought coverage on three dates. The New Yorker published a review titled "The Wealthiest—and Stealthiest—Class in America" on Sept. 13, 2026. Marketplace published a story about the book on Sept. 15, 2026. On Sept. 18, 2026, Bloomberg published a video interview with Zidar and Zwick about how they measured the actual number of rich people in America. Bloomberg

The broader context here is measurement. For researchers who work with tax data, linking firm and individual returns changes what can be learned about pass-through income, including how concentrated it is, how long it lasts, and the age and firm-size profile of recipients. De-identification keeps taxpayer information private while still allowing matches across business and individual filings.

In my view, the method matters more than the cover count of millionaires. Surveys often miss very rich households and struggle to value private businesses. Administrative linkage records profit as reported for tax purposes, matched to the owner. That shortens the distance between income measurement and legal business structure.

Looking at what this means for applied work, the closely held, mid-market finding points future research toward governance, succession, reinvestment, and tax treatment of pass-through entities. Models that place top business income only at large public firms or with retirees will miss where the administrative data finds much of it.