… is from page 97 of the 18th (2013) edition of Roger LeRoy Miller’s, Daniel Benjamin’s, and 1993 Nobel laureate Douglass North’s book, The Economics of Public Issues:
[A] substantial part of the rapid income growth at the top has really been a matter of accounting fiction, rather than reality. Until the late 1980s, there were substantial tax advantages for the very wealthy to have a large portion of their incomes counted as corporate rather than personal income. In effect, a big chunk of income for the wealthy used to to be hidden, not from the tax authorities, but from the policymakers who worry about the distribution of income. Subsequent changes in the tax laws have since encouraged people to report this income as personal rather than corporate income. Their incomes haven’t really changed; it just looks to policymakers like they have.