While trying to sell the GOP tax plan as a benefit for the middle class, Rep. Diane Black (R-Tenn.) argued on Monday that it’s hard to tell whether millionaires are in the middle class or are considered “rich.”

Fox Business host Trish Regan pressed Black, who chairs the House Budget Committee, about whether the GOP tax plan would actually hurt wealthy taxpayers. She asked how “socking it to the rich” would help Republicans curry favor with the middle class.

“Well I don’t know that you would call that ‘socking it to the rich’ if there wasn’t a decrease in the marginal rate because there are some other things that will help those who are at the higher income level,” she said.

Tom Williams/CQ Roll Call via Getty Images Rep. Diane Black (R-Tenn.) argues that it's hard to tell when someone is rich.

“I’m always careful about calling people rich because, what’s rich? Is $1 million rich? Is $10 million rich? Is $1 billion rich? So I want to be careful about that. But we really want to be sure that ... there are some pieces in there besides just the marginal rate, such as getting rid of the [alternative minimum tax]. There are some other pieces in there that do help those at upper income.”

To answer Black’s questions, yes, you are rich if you have $1 million, $10 million or $1 billion. A net worth of just $630,754 would put you among the wealthiest 20 percent of Americans, according to 2011 census data.

The line may be fuzzy around the $1 million mark for the congresswoman, who is running for governor of Tennessee, because she is worth far more than that.

Black’s net worth was more than $75 million in 2015, the latest year available on OpenSecrets.org. In 2011, The Atlantic ran a piece about Black called, “The Richest New Member of the House” and noted that much of her money came from “her interest in Aegis Sciences Corporation, a Nashville forensic chemical and drug-testing laboratory that her husband, David, founded in 1986.”

Black did grow up poorer, though, spending her first few years in public housing.

The median household income in the U.S. was $59,039 last year. There is no set definition of “middle class,” but in politics the term tends to apply to people making vastly more money than most Americans.

The few details of the GOP tax plan that have been released so far suggest not every middle-class taxpayer would get a lower tax bill. Though the framework calls for lower marginal tax rates, it also simplifies the tax code by eliminating a vast array of deductions and exemptions, which benefit the rich but also most people with lower incomes.

The nonpartisan Tax Policy Center said in an analysis that by 2027 the plan would actually increase taxes for nearly a third of taxpayers with incomes between $50,000 and $150,000 and nearly two-thirds of taxpayers with incomes between $150,000 and $300,000.

Republicans are tweaking their plan and have said they want to avoid those middle-class tax increases. The problem is that if they give back more deductions and exemptions, their plan will lose even more revenue. That’s why they’re considering an extra tax bracket for people with higher incomes.

During the debate over expiring Bush-era tax cuts in 2012, Democrats wanted the top marginal tax rate for individuals to kick in for incomes above $200,000, which Republicans thought was too low a threshold. Congress ultimately set the top bracket around $400,000.