Social Security benefits may not provide as much income as many older Americans expect — and that’s before possible cuts are needed to address a projected shortfall a decade from now.

Baby boomers anticipate that 47% of pre-retirement earnings will be replaced by Social Security, according to results of an annual survey from the Nationwide Retirement Institute. But the reality for someone making what the Social Security Administration considers the average wage in recent years, about $60,000, is more like 37%, according to the Committee for a Responsible Federal Budget. And the percentage drops as household income rises.

“We often see people form unrealistic expectations about what they will receive from Social Security and assume it is significantly greater than it truly is,” said Tina Ambrozy, senior vice president of strategic customer solutions at Nationwide. “For Boomers who are closer to retirement and may be relying on this income, this can be particularly detrimental to their finances.”

Many older Americans are already wondering how they’ll afford a retirement that could last 30 to 35 years, and that, according to some surveys, requires $1.8 million. The average Baby Boomer’s 401(k) account balance at Fidelity Investments is around $220,900.

The economic impact of America’s savings shortfalls could be huge: In 2040, America’s retirement crisis could cost federal and state governments an estimated $1.3 trillion in higher public assistance costs, lower tax revenue, decreased household spending and a drop in standards of living, according to a report done for the Pew Charitable Trusts.

The percent of pre-retirement income that Social Security replaces can vary greatly, depending on how benefits and earnings are calculated. Shifts to address a projected 2033 shortfall could also change total expected benefits. But if no action is taken — as waves of boomers leave the workface and fewer younger workers are sending payroll taxes into the pay-as-you-go system — current benefit levels could be cut by 23%, according to the Congressional Budget Office.

Nationwide’s national survey of 1,806 Americans age 18 or older, who get or expect to get Social Security, was done by Harris Poll between May 18 and June 13.

This article was provided by Bloomberg News.