Correction appended, Jan. 28, 2016

Ever since Walter Mondale lost the 1984 election by a landslide after saying he would raise taxes, the conventional wisdom has been that it was the worst thing a presidential candidate could say. Bernie Sanders doesn’t buy that.

“We will raise taxes,” the Vermont Senator told a crowd at the CNN Democratic town hall this week. “Yes, we will.”

Sanders, who is neck-and-neck with Hillary Clinton in Iowa and leading New Hampshire, has proposed an array of ambitious new government programs, from free college tuition and paid family leave to universal health care, and recently dropped a new tax plan explaining how he’d pay for it all.

The upshot?

“It’s a very, very, very big tax increase for everyone except those at the bottom,” Roberton Williams, a fellow at the Urban-Brookings Tax Policy Center, told TIME.

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In an analysis released today, the Tax Foundation, an independent tax policy research organization, found that Sanders’ plan would lead to 10.56% lower after-tax income for all taxpayers, and a 17.91% lower after-tax income for the wealthiest Americans. When accounting for reduced GDP, taxpayers would see their after-tax incomes fall by 12.84% on average, the report said.

Williams was more cautionary. “There are also a lot of moving pieces,” he explained. “It’s a big tax increase, but there are all these goodies on the other end. So there will be winners and losers.”

Take, for example, Sanders’ plan to provide universal, single-payer healthcare. Sanders says he’d pay for that with a new 2.2% income-based “health care premium” tax, as well as a 6.2% payroll tax paid for by employers. That adds up to a big increase—but it also means that, in exchange, Americans would save the thousands of dollars they spend every year on premiums, deductibles and other out-of-pocket health care costs.

The typical American family of four covered by an employer-sponsored health care plan paid $24,671 last year on health care costs alone, according to the non-partisan Milliman Medical Index.

“The savings that Americans would gain by the elimination of private insurance premiums and deductibles are much greater than the public insurance premiums they would pay under Bernie’s plan,” Warren Gunnels, Sanders’ policy director told TIME.

“The typical family of four making $50,000 a year would pay less than $46 a month under Bernie’s plan for three months of paid family and medical leave and universal health care,” he said.

“This is not a tax hike,” he added. “It’s a major cost savings.”

In addition to the health care premium and payroll tax, Sanders also proposes a raft of other income-based tax hikes that he says will pay for other programs, such as expanding Social Security and providing paid family leave: a 0.4% payroll tax, a shift to tax capital gains and dividends as ordinary income, an elimination of the existing Social Security payroll tax exemption for earnings above $250,000, etc. The list goes on—and it starts to add up.

In a detailed analysis, Dylan Matthews at Vox estimates that Sanders’ proposed income-based tax hikes alone—ignoring Sanders’ other proposed taxes, such as those on carbon and financial transactions—would pencil out to an 8.8 percentage point increase for those with income below $250,000.

Howard Gleckman of the non-partisan Tax Policy Center estimates that the marginal tax rate for the richest Americans on the last dollars of income under Sanders’ plan would be 58%.

What’s clear is that those at the very top of the income ladder would definitely feel the Bern the most.

According to Sanders’ team’s calculations, which do not take into account the health care premiums, those who make more than $1 million a year would see their effective tax rates—in other words, the amount they pay after deductions and credits—on income alone increase from about 30% to 36%. Those who make more than $5 millionwould see it increase from 29% to 47%.

Add those tax increases to Sanders’ proposed new taxes on investment income and the effective tax rate starts to climb.

Matthews estimates the rate for the richest bracket would be closer to 77%—a number we haven’t seen since 1964, back before income inequality was a thing. (Unlike Gunnels, Matthews includes in his calculations Sanders’ 2.2% health care premium, plus the Affordable Care Act’s 3.8% surtax on investment income, which Sanders’ plan would keep in place, plus the 6.2% employer-paid health care premium, which he assumes will be passed onto employees, as it usually is.)

Sanders’ plan would also hit the wealthy in other ways. It would expand the estate tax, cap the value of deductions at 28% for those making $250,000 or more, and levy a tax on all financial transactions, such as trades as stocks, bonds, derivatives and other securities.

The financial transactions tax is a tiny surcharge—usually a few hundredths of one percent—levied on each trade. It would have an almost imperceptible effect on most Americans, who buy and sell in the stock market only occasionally, but it could skim as much as $185 billion over ten years from high-frequency traders and the rest of the hedge fund sets.

Sanders’ plan would also hike the capital gains tax on the upper income brackets. Those with taxable incomes above $250,000 would pay a 50% capital gains tax, and the very rich—those with taxable incomes above $2,000,00o—would pay more than 60% on that income.

All of these calculations, of course, suppose that Sanders’ tax plan has a snowball’s chance in Congress of actually passing. Which it does not. Even with a Democratic Congress. And even with a President Sanders in 2017.

Correction: The original version of this story misstated the effect a Tax Foundation analysis said Bernie Sanders’ tax plan would have on Americans’ incomes. The analysis said after-tax incomes would fall by 12.84% or more on average. The story also misstated which tax rate would top 58% for the richest Americans. It would be the marginal tax rate, according to the analysis.

Write to Haley Sweetland Edwards at haley.edwards@time.com.