who contribute money to the social security trust fund
Social Security Trust Fund The Social Security Administration collects payroll taxes and uses the money collected to pay Old-Age, Survivors, and Disability Insurance benefits by way of trust funds. When the program runs a surplus, the excess funds increase the value of the Trust Fund. At the end of 2014, the Trust Fund contained (or alternatively, was owed) $2.79 trillion, up $25 billion from 2013.[4] The Trust Fund is required by law to be invested in non-marketable securities issued and guaranteed by the "full faith and credit" of the federal government. These securities earn a market rate of interest.[5]