A retirement plan is a financial arrangement designed to replace employment income upon retirement. These plans may be set up by employers, insurance companies, trade unions, the government, or other institutions. Congress has expressed a desire to encourage responsible retirement planning by granting favorable tax treatment to a wide variety of plans. Federal tax aspects of retirement plans in the United States are based on provisions of the Internal Revenue Code and the plans are regulated by the Department of Labor under the provisions of the Employee Retirement Income Security Act (ERISA).