Employers' policies vary. Generally, workers can borrow up to 50 percent of their vested account balance up to a maximum of $50,000, according to the Internal Revenue Service. Employees repay the loan through payroll deductions.
More than 50 million workers are enrolled in 401(k)-type retirement plans.
Meanwhile, a separate study released Thursday reported that, of 1,000 workers polled, 46 percent said their defined contribution plans will be their most important source of monthly income in retirement, three times as many as those citing Social Security.
The study, by money manager BlackRock Inc., also found that 64 percent of employees think their employer should "care more about whether I achieve a financially secure retirement." BlackRock also polled 119 executives managing defined contribution plans, and about two-thirds agreed.
Carole Fleck is a senior editor at the AARP Bulletin.