Three Big Questions on Kamala Harris's Tax Policies .

As Vice President Kamala Harris moves quickly to launch her presidential campaign, voters are trying to quickly understand where she stands on taxes.

The best guess is that Harris's views on taxes closely resemble those of President Joe Biden, with a big-picture stance that wealthy people and businesses need to pay more, experts told MarketWatch.

That would set up a clear clash with former President Donald Trump, who has said he's ready to extend his signature 2017 tax law and possibly cut taxes further if he returns to the White House.

Before becoming vice president, Harris was a senator from California and a 2020 presidential candidate who said she would repeal Trump's Tax Cuts and Jobs Act, which has benefits for top earners and corporations.

At that time, Harris had tax proposals that skewed to the left of Biden's positions, tax-policy prognosticators noted this week. Her ideas included instituting a generous tax credit for low- and middle-income families and taxing stock, bond and derivative trades to fund healthcare coverage.

So there may be an easy case to make that Harris would press for higher taxes on rich people. But there's still a question of how she might do that - the same way Biden wants to, or differently?

"There are many open questions about Vice President Harris's ideas for tax policy," said Jon Traub, managing principal and tax policy group leader at the Washington National Tax office of accounting and consulting firm Deloitte.

Harris "has been so busy in the first few days of this new campaign that it is all but certain that deep policy dives into the tax code have been impossible," he said.

The Harris campaign did not respond to a request for comment.

Harris did mention taxes when she spoke at her campaign headquarters Monday, pegging Trump with "failed trickle-down policies that gave huge tax breaks to billionaires and big corporations and made working families pay the cost."

But there's a lot to sort out on taxes beyond talking points, and answers will need to come fast.

Portions of the Tax Cuts and Jobs Act that apply to individual taxpayers, including, for most, a cut to the income-tax rate, are expiring at the end of 2025. A full extension of the law would cost $4.6 trillion, according to the nonpartisan Congressional Budget Office.

Here are some of the big tax questions that lie ahead for Harris - and for voters who want to know what a Harris presidency would mean for their finances.

Will Harris keep Biden's pledge to not raise taxes on people making less than $400,000?
On the campaign trail and in office, Biden has consistently said he would not raise taxes on people who make less than $400,000 a year. It remains to be seen whether Harris will stick to that threshold.

"Is $400,000 still the magic number for making 'too much money' and the need to 'pay [their] fair share'?" asked John Stanford, a managing partner at Prism Group, a public-affairs firm advising corporations and nonprofit organizations. "I assume she stays with this, because it's now seared into the electorate's brain."

But when Harris sought the Democratic nomination before, she "didn't have any sort of hard-line pledge," said Erica York, a senior economist at the Tax Foundation, a right-leaning think tank.

"That's the biggest area to see whether there's continuity" between Harris and Biden, she said.

In this context, $400,000 isn't just a number, said Michael Linden, former executive associate director at the White House Office of Management and Budget during the Biden administration.

The $400,000 threshold encapsulated a "core idea that the most important problem the tax code has was wealthy people and corporations are not paying enough, that they are not paying their fair share," Linden said.

It was a way to frame the debate "and to be super clear with the American people that the president wasn't trying to raise taxes on the vast majority of Americans," he said.

If Linden's experience working on budget and tax matters at the White House is any clue, Harris and Biden have a lot in common on taxes. "I recall that the vice president and her team were very aligned with the policies that ended up coming out in the budget," he said.

What does Harris want to do about the corporate tax rate?
The Tax Cuts and Jobs Act permanently reduced the corporate income-tax rate to 21% from 35%.

As a candidate seeking the 2020 nomination, Harris said she wanted to return that rate to 35%.

If that's still the case, she would be seeking a steeper increase than Biden. The president has proposed boosting the corporate tax rate to 28%. Harris's proposed tax rate matters on several levels, Stanford said.

"Will she turn further against the business community - calling for higher corporate increase than Biden," he said, or is it a chance to "re-approach" the issue?

Trump, meanwhile, has floated the idea of taking the corporate rate down to 15%.

What about Harris's proposed tax on stock trades, and other ideas where she differed from Biden?
In 2019, when she was running for the Democratic nomination for president, Harris unveiled ideas for broadening healthcare coverage and lowering costs with her version of Medicare for All. Before that, she was one of the co-sponsors for the 2017 Medicare for All bill introduced by Sen. Bernie Sanders, an independent from Vermont who caucuses with Democrats.

Back then, Harris said in a Medium post that she would pay for the plan in part by taxing "Wall Street stock trades at 0.2%, bond trades at 0.1%, and derivative transactions at 0.002%. Think of it like this: that's a $2 fee on a $1,000 trade by investors and big banks," her post said.

Could a proposal to tax trades come back? "I don't think she'd run on a financial-transaction tax," York said. But even if Harris didn't campaign on such a tax, she would probably support such a proposal, York noted.

There are other tax questions about which Harris's past only reveals so much, she noted.

Harris pressed for a new tax credit geared at low- and middle-income families with and without children in her LIFT the Middle Class Act.

Under that 2018 proposal, income-eligible single filers under the income caps would have received up to $3,000 and married couples up to $6,000. Though phaseouts would have varied, $100,000 was the final cutoff for any tax credits, which could have been collected as monthly payments.

That sounds a lot like the monthly installments the IRS paid to parents in 2021, when Democrats boosted the child tax credit under the pandemic-era American Rescue Plan.

The Harris proposal would have been on top of the child tax credit and the earned-income tax credit. It would have been expensive, costing approximately $3.1 trillion, according to 2018 estimates from the Penn Wharton Budget Model.

When it comes to Harris's future tax priorities, analysts noted they could only offer a preliminary view without knowing more details about which parts of the Tax Cuts and Jobs Act Harris might roll back.

The LIFT act amounted to a "supercharged" earned-income tax credit, York said. But it's also "ancient history," she added. The Democrats' focus now could be on the child tax credit in the wake of the 2021 increase and its looming decrease to $1,000 from $2,000, she noted.

"It's reasonable to assume a Harris administration would pursue similar priorities to the Biden administration," said John Gimigliano of KPMG, where he is principal in charge of federal legislative and regulatory services in the firm's Washington-focused practice. But he's expecting Harris to "put her own stamp," as she did with her LIFT proposal.

For him, one of the biggest questions is who might become Treasury secretary if Harris wins. "More than anyone else in the administration, that person will have their hands on the wheel in steering tax policy," he said.

At Deloitte, Traub said Harris's 2019 tax proposals were part of her bid to become the Democrat standard bearer. But candidates typically tack to the middle after winning the nomination, he noted.

"So it would be surprising to me if she tried to resurrect some of these ideas between now and November," he said.

What personal-finance issues would you like to see covered in MarketWatch? We would like to hear from readers about their financial decisions and money-related questions. You can fill out this form or write to us at readerstories@marketwatch.com. A reporter may be in touch to learn more. MarketWatch will not attribute your answers to you by name without your permission.

-Andrew Keshner

This content was created by MarketWatch, which is operated by Dow Jones & Co. MarketWatch is published independently from Dow Jones Newswires and The Wall Street Journal.