Direct answer
What is the difference between SSI and SSDI?
The core difference is that SSDI is insurance earned through work credits, while SSI is a needs-based program with income and resource limits and no work requirement.
Both programs use the same medical definition of disability, but they are funded and awarded differently. SSDI is paid from the Social Security Trust Fund; SSI is paid from general federal tax revenue.
Sourced from ssa.gov — see citations below.
What is SSDI?
SSDI is disability insurance paid to workers with enough work credits.
What is SSI?
SSI is a needs-based program for disabled or elderly people with very limited income and resources ($2,000 individual / $3,000 couple).
Can I qualify for both?
Yes — this is called "concurrent benefits."
Topics
Sources
Every figure and rule on this page is drawn from official SSA publications. Verify at the links below.
- SSA — SSI vs SSDI Comparison (ssa.gov)