This article concerns proposals to change the Social Security system in the United States. Social Security is a social insurance program officially called "Old-age, Survivors, and Disability Insurance" (OASDI), in reference to its three components. It is primarily funded through a dedicated payroll tax. During 2015, total benefits of $897 billion were paid out versus $920 billion in income, a $23 billion annual surplus. Excluding interest of $93 billion, the program had a cash deficit of $70 billion. Social Security represents approximately 40% of the income of the elderly, with 53% of married couples and 74% of unmarried persons receiving 50% or more of their income from the program. An estimated 169 million people paid into the program and 60 million received benefits in 2015, roughly 2.