Even though Cox Machine Inc. offered employees a company match, less than half of new employees signed up for the company's 401(k) plan.

“We really wanted to help employees build up their retirement savings,'' recalled Stormie Myers, human resources manager for the Wichita, Kan.-based aircraft parts manufacturer.

That help came in 2011 when Cox Machine added a feature to the 401(k) plan: New employees who didn't say yes or no would be automatically enrolled in the plan.

Under that feature, an amount equal to 3% of employees' annual salaries would be contributed to the 401(k) plan, with the company matching 50% of those contributions. Then, in succeeding years, employees' contributions would be increased by 1 percentage point each year until hitting 6% of their pay. The 50% company match also would continue.

With that change, the 401(k) participation rate at Cox Machine soared to 75%. Automatic enrollment “has greatly increased employee participation,” Ms. Myers said, adding that the feature is good for employees and the company.

“It helps keep them from looking elsewhere and helps build their retirement savings,” she said.

Cox Machine is one of a growing number of employers that has added an automatic enrollment feature to their 401(k) and other defined contribution plans. The goal is to boost employee participation in the retirement savings plans. Close to 60% of U.S. employers now offer automatic enrollment in their savings plans, according to benefits consultant Aon Hewitt, compared with less than 20% in 2005.

Other employers also report big increases in employee participation rates through automatic enrollment. “We had been just under 60% and now are at about 80%,” said Andrea Darrow, manager of retirement programs at Hendrick Automotive Group in Charlotte, N.C., which added automatic enrollment in 2011.

“We want to take care of our employees and be sure they have a nest egg to fall back on,” Ms. Darrow said.

“Automatic enrollment has absolutely been a great success in bringing employees into the plan and saving for their retirement,” said Chris Cannova, director of personnel services at the Archdiocese of Chicago, which added the feature to its 403(b) plan in 2008 following an earlier freeze of its defined benefit plan.

Many employers who have adopted automatic enrollment have enhanced the feature by adding an automatic escalation: The employee contribution percentage automatically increases each year until hitting a cap.

At Crowder Constructors Inc. in Charlotte, N.C., for example, the automatic enrollment program is designed so that amounts equal to 4% of employees' annual salaries are contributed to the company's 401(k) plan.

Then, through automatic escalation, the contribution percentage rises by 1 percentage point each year, until hitting 7%.

“We wanted to make a positive difference in the lives of our employees, and this is a way to do it,'' said Claudia Dodgen, Crowder's vice president of employee services.