A new analysis by IRS researchers and academics published Monday morning estimates that the richest 1% of U.S. households don’t report around 21% of their income, often using complex tax avoidance strategies that allow them to outmaneuver the federal government’s increasingly rare audits of the wealthy.

Led by two IRS researchers as well as Daniel Reck of the London School of Economics and Emmanuel Saez of the University of California, Berkeley, the new paper (pdf) finds that 6 percentage points of the richest households’ unreported income “correspond to undetected sophisticated evasion” such as offshoring, pass-through businesses, and other avoidance tactics.

Read more at Common Dreams.