Primer on Disability Benefits: Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) [August 1, 2014] [open pdf - 734KB]
"In general, the goal of disability insurance is to replace a portion of a worker's income should illness or disability prevent him or her from working. Individuals may receive disability benefits from either federal or state governments, or from private insurers. This report presents information on two types of disability programs provided through the federal government: the Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) programs. SSDI is an insurance program that provides benefits to individuals who have paid into the system and meet certain minimum work requirements. In contrast, SSI is a means-tested program that does not have work or contribution requirements, but restricts benefits to those who meet certain financial eligibility criteria. Enacted in 1956, the SSDI program provides monthly benefits to insured disabled workers under the full retirement age (and to their eligible dependents) in amounts related to an individual's work history and career-average earnings in jobs covered under Social Security. SSDI beneficiaries are also eligible for Medicare following a 24-month waiting period. On the other hand, the SSI program--which went into effect in 1974--is a need-based program that provides a flat monthly cash benefit assuring a minimum income to aged, blind, and disabled individuals who have limited income and assets. In most states, SSI recipients are also eligible for Medicaid."
CRS Report for Congress, RL32279