Biden proposes billionaire's tax, aid for homebuyers. Here's what experts think.

President Joe Biden touted U.S. economic performance in his State of the Union Address on Thursday as he celebrated what he called "America's comeback."

Still, he struck a defiant tone when setting forth a vision focused on hiking taxes for wealthy individuals and corporations while improving prospects for the middle class.

"When they do well, the poor have a way up and the wealthy still do very well," Biden said. "We all do well."

Economists who spoke to ABC News lauded proposals to raise taxes on corporations and billionaires as sources of welcome potential revenue to address ballooning U.S. debt, but they cautioned about a slight cooldown of economic growth if some corporations opt to headquarter overseas.

A proposal of tax credits for first-time homebuyers elicited applause from economists about a much-needed jolt for the housing market, but some questioned whether the government support would be enough to make a substantial difference.

"Businesses are making a lot of money, and the wealthy have done very, very well," Mark Zandi, chief economist at Moody's Analytics, told ABC News. "That's the most logical way to go to raise revenue to address the long-term fiscal problem."

The White House did not immediately respond to a request for comment.

MORE: 7 takeaways from Biden's fiery State of the Union

Here's what economists said about the policies proposed in Biden's State of the Union address:

Billionaire's tax

Biden put forward a billionaire's tax that would set a minimum 25% tax for the nation's 1,000 billionaires, generating an estimated $500 billion in revenue over the next 10 years.

The measure would help eat away at U.S. debt while taxing funds with relatively little effect on economic output, Bruce Sacerdote, an economics professor at Dartmouth University, told ABC News.

The U.S. debt stands at a staggering $34 trillion and is on pace to grow an additional $20 trillion by 2033, according to a Congressional Budget Office report last year.

The federal debt amounts to one of "the biggest long term problems facing the country," Sacerdote said.

"Proposals that can raise revenue in ways that don't severely crimp economic activity make a lot of sense," Sacerdote added.

Over a roughly 30-year period from 1992 to 2020, the wealthiest 400 families in the U.S. paid an average inflation-adjusted income tax rate of 12%, according to a study in August from Danny Yagan, an economist at the University of California, Berkeley.