Brian Riedl uses a National Review Online column to address U.S. Rep. Alexandria Ocasio-Cortez’s proposal for 70 percent top marginal tax rates.

Representative Alexandria Ocasio-Cortez’s call for a 70 percent income-tax rate to finance green-energy initiatives has energized the Left. Yet this is completely destructive proposal. A 70 percent tax bracket would raise very little (if any) revenue, while damaging the economy and sending income and jobs overseas.

While details of Ocasio-Cortez’s energy proposal are unavailable, former Green-party presidential candidate Jill Stein has proposed a “Green New Deal” costing between $700 billion and $1 trillion per year for public jobs and clean energy initiatives. That is roughly 4 percent of GDP.

And when assessing the needed tax revenues, a green-energy initiative costing $7–$10 trillion over the decade should be examined in the context of $42 trillion in additional Democratic-socialist proposals that include single-payer health care ($32 trillion), a federal jobs guarantee ($6.8 trillion), student-loan forgiveness ($1.4 trillion), free public college ($800 billion), infrastructure ($1 trillion), family leave ($270 billion), and Social Security expansion ($188 billion).

That 21 percent of GDP cost would double federal spending. And that does not even account for a baseline budget deficit rising to 7 percent of GDP over the decade — bringing the total budget gap to 28 percent of GDP.

Even if taxing the rich could finance a Green New Deal costing 4 percent of GDP … that would use up all the plausible upper-income tax hikes that could otherwise address the remaining baseline deficits and new liberal spending initiatives that total 24 percent of GDP (an annual budget shortfall of $5 trillion in today’s dollars). The middle class would have to pay that remaining tab.