What is the difference between SSDI and SSI?

Social Security Disability (SSDI) is best thought of as an insurance program. A recipient has to have worked a certain amount in his or her lifetime to qualify for benefits. Supplemental Security Income (SSI) on the other hand is considered to be a form of welfare and is needs-based, meaning that a person must get very low income with very few assets in order to qualify. Both programs pay benefits to disabled persons who qualify under the physical and mental impairment guidelines set by federal regulations