A retirement plan insurance, also known as retirement income insurance or annuity, is a financial product designed to provide a steady stream of income during retirement. It works by the individual making contributions or purchasing the annuity contract from an insurance company.

Upon retirement, the insurance company pays out regular income payments, either for a specified period or for the rest of the individual's life. This helps retirees ensure they have a dependable income source to cover living expenses and maintain their desired lifestyle throughout retirement. Retirement plan insurance can offer protection against outliving one's savings and market fluctuations, providing peace of mind during retirement years.