Social Security has been known as “the third rail of American politics” since the early 1980s, with the idea that touching the program can prove deadly to a politician’s career. The program is on solid footing for now, but the Social Security Administration’s latest projections point to benefit cuts in 2035, unless Congress takes action.

On the campaign trail, the presidential candidates are promising to preserve the program and protect seniors, but snappy lines at campaign rallies can mask the complexities of the issue.

“I think there’s a real difficulty in talking about Social Security, because there’s been so much storytelling,” said Romina Boccia, director of budget and entitlement policy at the Cato Institute. “And there’s so many myths out there about how the program works.”

For years, the system has been paying out more in benefits than it brings in in payroll taxes, partly due to the combination of lower birth rates and an aging population.

Another reason is growing income inequality.

There’s a cap on the income that’s taxed for Social Security,  so the Americans who earn the most — and their employers — only pay Social Security taxes on the first $168,600 of income.

Stephen Goss, the chief actuary of the Social Security Administration, explained the issue to members of Congress in testimony before the House Budget Committee earlier this month.

“The earnings of the top 6% of workers whose earnings exceed the taxable maximum level under Social Security unexpectedly grew considerably faster than for the other 94% of workers between 1983 and 2000,” he said, “lowering the percent of covered earnings that is actually taxable from 90% in 1983 and expected in the future, then to just 82.5% by the year 2000 and thereafter.”

The program covers the difference between taxes that come in and benefits that go out by tapping its trust fund, built from past Social Security surpluses invested in Treasury bonds, plus the interest on those bonds.

“There is a problem in 10 or 11 years down the road, when those reserves — the trust fund — will be used up, and all that will be left is current payroll taxes,” said Max Richtman, president and CEO of the National Committee to Preserve Social Security and Medicare. That would prompt automatic benefit cut, where “people will be getting 86-87% of their benefits and we don’t want that. We want full benefits.”

By law, Social Security can’t take on any debt or tap into general revenues to fund benefits, so Congress needs to do something before the money runs out, said Cato’s Romina Boccia.

“Unfortunately, there is no silver bullet to fixing Social Security that doesn’t involve some form of tax increase or some form of benefit cuts, which is why I think it’s so important to have an honest conversation that there is no free lunch here,” she said.

But those kinds of honest conversations can be challenging to have in Washington — especially during an election year.