The plan would not raise taxes on people earning less than $400,000 a year. Instead, Harris wants to significantly raise taxes on the richest Americans and large corporations. Congress has rejected many of these tax proposals before, even when Democrats controlled both chambers.

While tax policy is currently just a subplot in a tumultuous presidential campaign, it will be a central political issue in Washington next year. The next president will have to work with Congress to address the tax cuts that (then-President) Donald J. Trump signed into law in 2017. Many of those tax cuts expire after 2025, meaning millions of Americans could face rising taxes if lawmakers don’t reach an agreement next year.

Harris’ plan would raise the top income tax rate from 37% to 39.6%, while increasing the Medicare surtax for Americans earning over $400,000 a year from 3.8% to 5%. At the same time, capital gains for those earning over $1 million a year would be taxed at the same rate as regular income.

“The super-rich don’t make their money the way most people do. Their money comes from owning businesses, real estate, financial assets and inheritances,” economist Michael Linden said in a social media post on Wednesday. “These types of income all enjoy special tax advantages, and because of this, they end up paying less than middle-income Americans.”

On Thursday, Democratic U.S. Senator Elizabeth Warren of Massachusetts said: “It is outrageous that billionaires pay less in taxes than public school teachers. It is time we made the rich pay their fair share. My ultra-millionaire tax would do just that.”

In March, Warren and Representatives Pramila Jayapal (D-Wash.) and Brendan Boyle (D-Penn.) introduced an updated version of a 2021 bill that they said would raise at least $3 trillion over 10 years by imposing a 2% tax on wealth over $50 million. The bill also imposes a 3% tax on the wealthiest households overall, with an annual surcharge of 1% on the net worth of households and trusts over $1 billion.

Last year, Reps. Steve Cohen (D-Tennessee) and Don Beyer (D-Virginia), with the support of numerous Democrats in the House, reintroduced the Billionaire Minimum Income Tax Act. The bill — drafted in coordination with the White House and the U.S. Treasury Department and supported by dozens of labor and progressive groups — would amend the Internal Revenue Code to include unrealized gains in a minimum tax on certain wealthy individuals.

Senator Ron Wyden (Democrat of Oregon) introduced a version of the bill in the upper house along with 15 of his colleagues.

Meanwhile, Trump, the Republican presidential nominee, has promised to extend the tax cuts from his $1.5 trillion plan, which was derided as the “Republican tax scam” when he signed it during his first term in the White House. A 2023 analysis by the progressive advocacy group Americans for Tax Fairness found that the total wealth of U.S. billionaires skyrocketed by more than $2 trillion in the years after Trump signed the tax cuts.