But other features vary from plan to plan, depending on any given employer's choices.
Some plans are voluntary, while others require employees to participate.
Some plans have waiting periods between when you start work and when you can enroll in the plan. Some plans also have minimum ages for eligibility. Contribution rates, usually set as a percentage of each employee's salary, vary from employer to employer and may also vary according to employees' ages. When you can begin receiving retirement income varies from plan to plan. Age 65 is standard but by no means universal.