Remember when George W. Bush tried to privatize Social Security? I was very involved in that debate, and one thing I learned was that well-off Americans, who typically have substantial sums stowed away in their 401(k)s and have other assets besides, often have little sense of just how important Social Security is to their less affluent fellow citizens. Benefits from the program make up more than half of many retirees’ incomes; a substantial number have almost nothing else to live on.

So it’s important to be aware that one effect of Donald Trump’s economic proposals, if enacted, could be to drive Social Security into bankruptcy, impoverishing many older Americans — not in the distant future, but within around six years. And while I have in the past assumed that Social Security will be bailed out if necessary, that looks less certain in the antidemocratic nation we may become if Trump wins.

First things first: Social Security is a government program, counted as part of federal spending. So how is it possible for an individual program to go bankrupt if the federal government as a whole remains solvent (which, despite Trump, it probably will)?

The answer is that Social Security has its own, separate budget. If you get pay stubs, you’ll see that there’s a deduction for FICA, the federal payroll tax. Your employer pays an equal amount, and when you include the employer share, around two-thirds of Americans pay more in payroll taxes than they do in income taxes. Most of these payroll tax receipts are dedicated to Social Security (the rest support part of Medicare).

This system, in which contributions from working-age Americans pay for benefits to seniors, has been placed under pressure from an aging population, which has increased the ratio of beneficiaries to workers. But everyone knew long ago that baby boomers would eventually stop paying in and start taking money out, so way back in the 1980s steps were taken to shore up Social Security’s long-term finances. These steps included increasing the payroll tax rate, making benefits subject to income tax and gradually raising the age of eligibility for full benefits from 65 to 67.

These actions allowed Social Security to run large surpluses for a couple of decades and accumulate a trust fund that could be used to help pay benefits once baby boomers began retiring. The plan was to keep the system actuarially sound for 75 years, but the fix appears to be falling short, largely because of rising inequality. Under current policy, Congressional Budget Office projections suggest that the trust fund will be exhausted in 2034. At that point, the budget office estimates, benefits would have to be reduced immediately by 23 percent, and potentially by a greater percentage in future years, to bring them in line with revenues, unless something else was done to close the gap.