What is the difference between Social Security Disability (SSD) and Supplemental Security Income (SSI)?

SSD is a disability insurance program that you pay into when you work and earn work credits. The amount you receive each month from SSD, if approved, is based on how much money you have earned over your lifetime. SSI is also a disability program with the same medical requirements as SSD; however, you do not need work credits to be eligible to apply for SSI. SSI does, however, require that you meet certain income/asset/resource guidelines as well. If medically approved for SSI, certain forms of income/assets/resources can affect the amount you receive.