Taxes are going up. Maybe not soon, but the mushrooming national debt will eventually leave Washington no choice but to hike taxes. And the longer we wait, the more it will hurt.

The Congressional Budget Office recently forecast annual federal deficits of more than $1 trillion for 2020, and each of the next 10 years. By 2030, CBO says, the deficit will hit $1.7 trillion. Economists generally think a fiscal deficit of around 3% of GDP is healthy and manageable. U.S. deficits over the next decade will average 4.8% of GDP.

Annual deficits spiked during the Great Recession, when tax receipts plunged and stimulus spending soared. The $1.4 trillion deficit in 2009, at the nadir of the recession, was the worst on record.

Deficits fell sharply as the economy recovered, however, and hit a post-recession low of $442 billion in 2015. Then they ticked up again, mostly because of runaway health spending on Medicare and Medicaid. Then came the Trump tax cuts, which went into effect in 2018.

Those tax cuts pushed corporate tax revenue to the lowest levels ever as a portion of federal revenue. Tax revenue from individuals has gone up slightly, because of economic growth. But it would have gone up more without the Trump tax cuts, or with cuts limited to middle- and lower-income workers, say. The twin effect of depressed federal revenue and health care costs growing faster than the economy are driving those trillion-dollar deficits.

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This isn’t a crisis today, even though some economists thought it would be by now. But widening deficits at this level aren’t sustainable, either, because they’ll crowd out private investment and depress productivity. Growing interest payments on all that debt will leave less and less for highways, airports and everything else taxpayers expect after mandatory health and retirement spending.

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Will Americans tolerate the sharp cuts in social programs and defense that are one way to close this gaping budget gap? Eh, maybe, a little, possibly. But tax hikes will be part of the prescription too, and the Brookings Institution’s Hamilton Project recently published a comprehensive list of the soundest options. Here are five types of tax hikes that would reduce Washington’s indebtedness:

A new inheritance tax. The average tax rate on income is 15.8%. On inherited wealth, it’s just 2.1%. The estate tax is meant to limit the growth of family dynasties and an American aristocracy, but it’s so weak and riddled with loopholes that it barely raises any revenue at all any more. A new inheritance tax would tax wealth received by an heir as normal income. There’d be an exemption threshold, so those subject to the tax would probably be paying at the top rate of 37%. At an exemption threshold of $2.5 million, this tax would raise $34 billion per year, according to the Tax Policy Center. At a lower threshold of $1 million, it would raise $92 billion. That’s a start.

A wealth tax. Policymakers and politicians have gotten interested in wealth taxes because the richest families in America earn most of their money from investing, rather than working. And there are several ways to defer and sharply reduce taxation on investments, which leaves the wealthy paying lower tax rates than ordinary working stiffs. Democratic presidential candidates Bernie Sanders and Elizabeth Warren both favor a wealth tax to fund programs such as free college and government-paid health care.