A qualified plan established by employers to which eligible employees may make salary deferral (salary reduction) contributions on a post-tax and/or pretax basis. Employers offering a 401(k) plan may make matching or non-elective contributions to the plan on behalf of eligible employees and may also add a profit-sharing feature to the plan. Earnings accrue on a tax-deferred basis.

Watch: Introduction in 401(k)

Caps placed by the plan and/or IRS regulations usually limit the percentage of salary deferral contributions. There are also restrictions on how and when employees can withdraw these assets, and penalties may apply if the amount is withdrawn while an employee is under the retirement age as defined by the plan. Plans that allow participants to direct their own investments provide a core group of investment products from which participants may choose. Otherwise, professionals hired by the employer direct and manage the employees' investments.