A 401(k) plan is a defined contribution plan, typically a profit sharing plan, that contains a cash or deferred arrangement as described in section 401(k) of the Internal Revenue Code. A cash or deferred arrangement is simply an arrangement that allows plan participants to elect to defer a portion of compensation, their elective deferrals, and have it contributed to the plan on their behalf, typically through payroll withholding.
A 401(k) plan may allow participants to elect “Roth” tax treatment of all, or a portion, of their elective deferrals. Under Roth treatment, the elective deferrals are taxable when deferred, as opposed to the pre-tax treatment afforded to traditional 401(k) elective deferrals. If certain requirements are met, these Roth contributions can be distributed tax free in the future.
In addition to making elective contributions, the employer may contribute to the plan by matching all, or a portion, of the elective deferrals or by making non-elective, or profit sharing, contributions to all eligible participants.