The basics: SSDI and SSI

The US' two largest long-term disability programs are Social Security Disability Insurance (SSDI) and Supplemental Security Income, both of which are administered in the Social Security Administration (SSA). SSDI is part of the Old-Age Survivors and Disability Insurance program administered by the SSA, the same program that funds retirement benefits for seniors. SSDI benefits are funded by worker to Social Security; of the 12.4% payroll tax paid by workers and employers, about 15% is paid to the Disability Insurance Trust Fund (the remainder goes to the trust fund for old-age retirement benefits).