The U.S. Department of Treasury published a Fact Sheet regarding how the tax compliance proposals will improve tax fairness while protecting taxpayer privacy.
In it the Treasury states "Rates of tax compliance in the United States are based in large part on the ways taxpayers accrue income. Those who receive their income that is reported on by a third-party source, such as wage earners, exhibit near-perfect compliance rates on their salaries–since the payer of the income also reports the income paid as a deduction.
By contrast, taxpayers who accrue income in hard-to-trace ways exhibit much lower rates of compliance, as there is no third-party source that reports income to tax authorities. Instead, these taxpayers take advantage of the fact that certain income streams are hidden from the IRS, with no information that the IRS can use to detect noncompliance."
In a Tweet from Secretary Janet Yellen she said "Today’s Congressional tax compliance proposal reflects the Administration’s strong belief that we should zero in on those at the top of the income scale who don’t pay the taxes they owe, while protecting American workers who do."
And posted an image of her full statement.