In a clip aired Tuesday evening, CBS News’ Norah O’Donnell asked Yellen regarding the plan, “Does this mean that the government is trying to peek into our pocketbooks if you want to look at $600 transactions?”

“Absolutely not,” the treasury secretary replied, insisting, “I think this proposal has been seriously mischaracterized. The proposal involves no reporting of individual transactions of any individual.”

Then Yellen went into how there are “individuals” the IRS does not receive enough information about.

“Look, the big picture is that we have a tax gap that over the next decade is estimated at $7 trillion,” she continued. “Namely, a shortfall in the amount that the IRS is collecting due to a failure of individuals to report the income that they have earned.”

O’Donnell asked, “But that’s among billionaires. Is that among people who are transferring $600?”

“No, it tends to be among high-income individuals whose income is opaque and the IRS doesn’t receive information about it,” Yellen said. “If you earn a paycheck, you get a W-2, the IRS knows about it.  But high-income individuals with opaque sources of income that are not reported to the IRS, there’s a lot of tax fraud and cheating that’s going on, and all that’s involved in this proposal is a few aggregate numbers about bank accounts – the amount that was received in the course of the year, the amount that went out in the course of a year.”

Yellen then gave an example.

“If someone reports an income of $10,000, and they had $3 million go out of their checking account, that tells the IRS that’s an individual that you might audit.”

Yellen has not explained the threshold for who the administration would consider “wealthy,” nor has she ruled out going after wage-earners.

This is also not the first time she has been asked about why the $600 proposal is so low if the IRS is purportedly targeting “billionaires.”