The Employee Retirement Income Security Act (ERISA) requires employers to give plan participants (employees) a summary of their plan, called the summary plan description or SPD. Provided for plan participants by the ERISA Trust Administrators, the SPD details for participants what the plan provides as well as how it operates. Additionally, the SPD provides additional critical information, including: when an employee can begin participating in the plan; how service and benefits are calculated; when benefits become vested and are paid; and, how to file a claim for benefits. In the event that a plan is changed, participants must be informed of those changes by the ERISA Trust Administrators.