WASHINGTON—Presidential candidate Bernie Sanders is trying to expand federal taxation on a scale not seen since World War II, pursuing policies that would end the nation’s run as one of the industrialized world’s lowest-taxed countries.

Mr. Sanders’s combination of taxes on wealth, income, financial transactions, corporate profits, payrolls, estates and capital gains would hit rich Americans from every direction. If Congress were to pass all his plans, the total U.S. tax burden—including federal, state and local taxes—would resemble Canada’s or Germany’s rather than being near the bottom of the pack of rich nations.

Mr. Sanders views higher taxes as a means to pay for bigger health-care, housing, education and climate-change programs, and those plans would cost at least $40 trillion over a decade, according to the campaign, or a 66% increase in federal spending. And he seeks to stick companies and the top 1% of households with most of the bill.

“In developing our tax policies, our major goal is to make sure that we are reducing the massive level of income and wealth inequality that exists in America today,” said Warren Gunnels, a senior adviser to Mr. Sanders.

Independent analyses have cast doubt on whether Mr. Sanders’s proposals add up, suggesting that the campaign overestimates how much money his taxes would raise and underestimates how much the new programs would cost. Mr. Sanders disputes that.

He also doesn’t explicitly advocate more deficit spending, aiming to show that his tax increases, nontax revenue increases and some spending cuts will cover the costs of his new programs. His aides also point to his votes against tax cuts and wars as evidence of a Sanders style of fiscal hawkishness.


His proposed tax increases top $30 trillion over a decade, by the campaign’s own reckoning. That is more than 10% of gross domestic product and at least a 60% increase in taxes over what would happen otherwise.

The last U.S. tax increase of this magnitude occurred from 1942 to 1944, during World War II, when the income tax was expanded to the middle class, raising federal revenue to 20.5% of gross domestic product from 9.9%.

Former Vice President Joe Biden picked up wins across the South and dealt a blow to Sen. Elizabeth Warren after winning her home state of Massachusetts. Sen. Bernie Sanders picked up California, the state with the most delegates. Photo: (L) Allison Zaucha for The Wall Street Journal, (R) Cheryl Senter for The Wall Street Journal

“You made the income tax a mass tax, which was a big deal,” said Mark Mazur, who was the top Treasury Department tax-policy official in the Obama administration. “This is like five of those.”

Since World War II, U.S. federal revenue has stayed between 14.2% and 20% of GDP, and is slated to average 17.4% over the next decade. Mr. Sanders’s proposed tax increases would send that level past 28%.


“These are unprecedented tax increases. These are huge,” said Nicole Kaeding, an economist at the National Taxpayers Union Foundation, a nonprofit research group affiliated with a conservative organization.

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Almost all of Mr. Sanders’s proposed tax increases—except for middle-class taxes designed to replace insurance premiums and out-of-pocket health-care costs—target the top of the income and wealth distribution, the millionaires and billionaires he castigates on the campaign trail.

The Progressive Policy Institute, a center-left group, estimates that his proposed spending would exceed revenue by $25 trillion over a decade, with much of the gap due to estimated costs of his Medicare for All program. Mr. Sanders’s aides say their plans add up.

At some level, what separates Mr. Sanders from other Democrats on tax policy isn’t necessarily direction but degree. Former Vice President Joe Biden, who is Mr. Sanders’s chief remaining rival, along with the party’s leading tax-policy thinkers and its former presidential candidates, all want to raise taxes, concentrating on high-income households. They want to reverse parts of the 2017 tax law, let people shield less money from the estate tax and close the tax-rate gap between investment income and wages.


“I favor higher taxes on high-income people,” said Austan Goolsbee, an economist who worked for President Obama and supported former South Bend, Ind., Mayor Pete Buttigieg’s campaign. “I don’t think Bernie or the other Democratic candidates are wrong that we are in a historical abnormality of tax giveaways to high-income people and big corporations. The question is: Is it conceivable to get $20 trillion of taxes just from high-income people?”

Mr. Sanders’s proposals top all the others. He would set the top individual income-tax rate at 52%, compared with Mr. Biden’s proposed 39.6%. He would impose an annual wealth tax that tops out at 8%, above the 6% rate favored by Sen. Elizabeth Warren (D., Mass.), who ended her campaign Thursday. He calls for a 35% corporate tax rate with tighter rules on foreign profits, compared with the 28% rate sought by former New York Mayor Michael Bloomberg, who suspended his bid this week.

As with Ms. Warren’s plan, the combination of the wealth tax and other levies could lead to tax rates above 100% for some of the very wealthiest people when measured as a share of income.

“It would stabilize the wealth of billionaires,” said Gabriel Zucman, an economist of the University of California, Berkeley, who advised the Sanders and Warren campaigns on wealth taxes.


Mr. Sanders’s proposals could combine with each other for tax rates the U.S. hasn’t seen in decades. For wages, a person with income topping $10 million would pay a 52% top rate in addition to the existing 3.8% Medicare tax, a 12.4% Social Security tax that Mr. Sanders is expanding to high earners, a 4% Medicare for All tax and a 7.5% Medicare for All tax owed by employers.

Technically, some of the payroll taxes would be paid by employers, but economists generally believe that workers eventually bear that cost. Similar tax rates would apply to capital gains and business income.

He would repeal the cap on the state and local tax deduction, but place a $50,000 limit on all itemized deductions. Very high-income households would exceed that cap and face their marginal state income-tax rates on top of federal taxes. In California, for example, that is a 13.3% rate, so the next $100 of wages of income of someone in the top tax bracket could yield more than $80 in taxes.

And, for high-income households, that rule would sharply limit deductions for charitable contributions. In Mr. Sanders’s vision, tax-funded government programs would fill any gap left by the erosion of tax-advantaged charities, and he sees that as a plus.

“By establishing an economic bill of rights—similar to what FDR proposed in 1944—every American would have the fundamental right to a good paying job, housing, a secure retirement, health care, education, and a healthy environment,” Mr. Gunnels said. “In the richest country in the history of the world, no family in America should have to depend on charitable donations from billionaires for the basic necessities of life.”

Those taxes differentiate Mr. Sanders’s interpretation of democratic socialism from the European countries he often cites as models. In those countries, top income-tax rates generally start at lower income levels than in the U.S. and value-added taxes—levies on sales and consumption—spread the burden of larger government across the whole population.

“Bernie’s never been a big fan of the VAT because that is a regressive tax in nature,” Mr. Gunnels said. “It’s essentially a sales tax.”

The European model relies on broad, regressive taxes to pay for broad, progressive government benefits. Mr. Sanders, in contrast, wants large, progressive tax increases on a few to pay for broad, progressive government benefits.

“It’s important to talk about who should pay for them,” said Josh Orton, the campaign’s national policy director. “It’s important to talk about who actually should be contributing their fair share.”

Write to Richard Rubin at richard.rubin@wsj.com