Many U.S. workers are not rebalancing or increasing contributions to their employee-sponsored retirement plans as often as they should, according to a new study by TIAA-CREF.

Thirty-six percent of those who contribute to a plan have never increased the percentage of their salary they contribute, according to the survey, released today. Another 26 percent have not increased their contribution in the last year.

“Considering that 44 percent of American employees save 10 percent or less of their annual income each year, these findings indicate that many employees have the opportunity to improve their retirement readiness by increasing their plan contributions regularly,” retirement plan provider TIAA-CREF said in a press release.

One thousand adults who contribute to an employer-sponsored retirement plan participated in the survey.

Fifty-three percent of respondents were not automatically enrolled in their companies’ plans. Those not automatically enrolled lost time saving for retirement, TIAA-CREF says, with 37 percent waiting at least six months before enrolling and another 24 percent waiting a year or more.

The survey also found that 57 percent of workers did not increase their plan contribution after their last raise. The most common reason cited for not increasing contributions after a raise was an immediate need to pay expenses, says the study.

Men were more likely to be contributing the maximum (33 percent) than women (17 percent).

One-quarter of workers have never made changes to their investments, and 28 percent have not made changes in more than one year.