Tax avoidance by the top 1% is far worse than previously estimated by the IRS. Richard Rubin, writing for the 3/22/21 Wall Street Journal, reported that the top 1% fail to report (and pay taxes on) about 21% of their income. "For the top 0.1%, unreported income may be nearly twice as large as conventional IRS methodologies would suggest." Researcher Daniel Reck of the London School of Economics (in a U.S. National Bureau of Economics paper) reports that tax avoidance by the ultra wealthy is getting worse due to more sophisticated schemes.
"IRS audit rates and enforcement staffing have declined steadily for a decade amid budget cuts. President Biden and other Democrats have proposed reversing that trend with a significant expansion of the U.S. tax Agency."