It’s a bizarre subject to study. Researchers cannot know what “true income” actually is, but can only estimate it by looking at what IRS agents found in a sample of returns selected for intense audit.  One intriguing assumption they make is that the IRS examiner’s ability to find hidden income is correlated with her pay grade.

Very high income taxpayers, over $2,000,000, are estimated to have a much lower propensity to underreport than their $200K to $1 million brethren.  Do they hide less?  Perhaps, but there remains “the plausible possibility that the misreporting of upper-income taxpayers is more sophisticated and thus harder to detect.”

All the estimates of under-reporting are looking at the tax laws as they actually exist, and do not consider the various special-interest loopholes to be anything other than part of the rules (pretending, of course, that someone actually understands the income tax code).

A surprising result follows from the “progressive” nature of the income tax:  Even tho low income taxpayers hide relatively little income, their underreporting actually reduces their taxes by a much greater percentage than does that of the high income folks. [This is because, if your income is low, only a small part of it is actually subject to income tax.]