We need a tax system that raises enough revenue to finance critical needs and help prevent spiraling debt. As an aging population and rising health costs boost spending for Social Security and Medicare, and as America faces domestic challenges such as addressing our decaying infrastructure, we’ll need more revenues, not fewer.

While America faces a long-term fiscal challenge, the pending Republican tax legislation would make it more serious, thereby inviting subsequent proposals to slash core safety-net programs and basic governmental functions—all to provide $1.5 trillion in tax cuts that will mainly benefit large, profitable corporations and those at the top.

The legislation compounds the mistakes of policymakers in recent decades in shrinking federal revenues; at 17.3 percent of Gross Domestic Product today, revenue is already significantly below its level before the Reagan and Bush tax cuts. And, by itself, the Bush tax cut is responsible for a third of the entire federal debt. The fiscal pressure created by that has fueled policymakers’ decisions of recent years to shrink “non-defense discretionary spending” — all non-defense programs that aren’t entitlements, including education, job training, low-income housing, transportation, scientific research, environmental protection, and more — to close to its lowest level as a share of GDP in more than 50 years.

When the political pendulum swings in Washington, as it eventually will, Democrats should make progressive tax reform that raises more revenue an urgent priority. Here are some key components:

To start, they should undo the GOP tax legislation’s regressive and egregious elements, assuming they become law. These elements include shrinking or repealing the estate tax, which only heirs of the top two of every 1,000 estates pay; cutting the corporate tax rate to 20 percent, which would mostly benefit wealthy shareholders and corporate executives; providing an even lower corporate tax rate on their foreign profits, which is likely to encourage U.S.-based multi-nationals to move more jobs to low-tax countries; and creating a special low tax rate for “pass-through” income that would overwhelmingly favor the wealthy owners of partnerships, S corporations, and sole proprietorships and also fuel substantial new tax avoidance.

Instead, with wages largely stagnant for low- and modest-income working households, we need a tax system that uses refundable tax credits more aggressively to reduce poverty and boost incomes. Proposals on the table include one from Representative Ro Khanna and Senator Sherrod Brown to expand the earned income tax credit substantially for workers not raising children and to roughly double the maximum EITC amount for families with children, and one from Representative Rosa DeLauro and Senators Michael Bennet and Brown to increase the refundability of the Child Tax Credit and increase its size for families with young children.

Democrats also should curtail inefficient and regressive tax preferences that the GOP legislation leaves largely or entirely untouched. They should, for instance, reduce or eliminate the preferential treatment of capital gains and dividends. They must also eliminate the carried interest loophole that lets wealthy investment managers pay income tax at a sharply reduced rate. In addition, they should restructure incentives for retirement saving and saving for higher education, which currently do little for those who need such resources the most and squander resources on many affluent households that have adequate savings anyway.

With the population aging, Social Security will need a larger share of the nation’s resources in coming decades. When the political opportunity arises, the President and Congress should take steps to assure that Social Security can fully meet its promises and to strengthen benefits for particularly vulnerable groups. Any plan to address Social Security’s long-run funding shortfall should rely mainly on increasing its tax revenues. Options include raising or eliminating the cap on taxable wages ($128,400 in 2017), broadening the payroll tax base, and gradually raising Social Security payroll tax rates. The best approach will likely be a well-designed mix of all three.

Tax policy also must support a cleaner environment. With unabated greenhouse gas pollution from burning carbon-based fossil fuels risking catastrophic environmental damage, economists broadly agree that “putting a price on carbon” to raise the price of fossil-based energy and encourage alternative clean technologies would help address the challenge. A well-designed carbon tax can generate enough revenue to enable policymakers to fully offset the higher energy prices that households with modest incomes will face, cushion the impact for many other households, and leave some money to spare for other uses, whether funding other priorities or reducing the deficit.

Demographic, economic, and other factors are raising demand for many goods and services that the federal government can produce most effectively and efficiently, such as Social Security, health insurance, long-term investments in education and infrastructure, and basic scientific research and development. Federal spending and revenues will consequently need to be larger as a share of the economy in coming years than in the past.

Policymakers have considerable room to raise revenues in sound, efficient ways that won’t hurt the economy and will finance investments that can raise living standards and the quality of life down the road.