SSISSI stands for Supplemental Security Income. Social Security administers this program. We pay monthly benefits to people with limited income and resources who are disabled, blind, or age 65 or older. Blind or disabled children may also get SSI. stands for Supplemental Security Income. Social Security administers this program. We pay monthly benefits to people with limited income and resources who are disabled, blind, or age 65 or older. Blind or disabled children may also get SSI.