Confusion, inertia and limited incomes may be some of the reasons 20 percent of American workers who are eligible for 401(k) programs never invest in them. Moreover, that figure has remained fairly constant over the past five years, analysts report.

• The value of 401(k) plans has grown from $91 billion in 1984 to $1 trillion today.

• Benefits consultants say that in many instances people simply don't get around to signing up -- particularly in companies that require employees to wait a year or so before they qualify.

• Young workers in their 20s and 30s who may not be making a lot of money see retirement as a long way off and fail to take advantage of the benefits.

• Experts say that rarely do more than 50 percent of employees participate in companies where employers don't provide matching funds.

On the other hand, employers can encourage workers to sign up by having good matching programs, allowing employees to borrow from their accounts and offering six or seven good investment choices.

Employees who don't intend to stay long at a job may avoid signing up because they don't understand that their 401(k) is portable and they can roll the money into a plan at a new employer or roll it into an IRA if they change jobs.

Although the Internal Revenue Service issued a ruling last year allowing companies to automatically enroll new employees in such plans, few companies do so. Under automatic enrollment, employees who do not wish to join must sign a form to stay out. McDonald's, which has had automatic enrollment for more than a decade, has a 95 percent participation rate.

Source: Sandra Block, "Workers Still Pass Up 401(k) Plans," USA Today, April 22, 1999.