Most non-retired Americans are well aware that they could maximize their Social Security payments if they delayed drawing benefits until the age of 70, but the vast majority plan to tap that income before then, according to a recent survey.

Eighty-six percent of non-retired Americans 45 and older know that their benefits would be greater if they waited until the age when they reach the maximum monthly benefit, but only 11% plan to wait, Schroders says it found in a nationwide survey of 1,000 U.S. investors ages 45 to 75 with a median household income of $75,000.

The survey was fielded February 17 to 28.

One reason for tapping Social Security before it’s maximized is the fear of the program running out of money or halting payments, cited by 32% of respondents, according to the survey.

In addition, 31% of respondents believe they’ll need the money before they turn 70, Schroders says it found.

Forty-eight percent of respondents plan to start tapping Social Security benefits between the ages of 62 and 65, another 19% plan to do it between the ages of 66 and 69, and 22% are unsure when, according to the survey.

“Delaying Social Security to increase your benefit is a tried and true means of generating more income in retirement, but it’s a path few are prepared to take,” Joel Schiffman, Schroders’ head of strategic partnerships, said in a statement.

Schroders says it also found that a large number of Americans approaching retirement simply don’t know how much money they’ll need. Of respondents between 60 and 65 years old, 23% “have no idea” what monthly income they’ll need to live comfortably in retirement.

“Given increasing life expectancies and widespread concerns about not being able to live comfortably without a paycheck, the advantages of creating a retirement income strategy that maximizes your Social Security benefits can’t be overstated,” Schiffman added.