Return to Videos SSDI is Social Security disability income, and that's income that you would get when you're disabled because you've been paying into a program, by way of your payroll taxes and your Social Security disability insurance tax. That goes along with virtually every on-the-books job that you have to have in the United States and your self-employment taxes and that pays for your disability insurance or your monthly payments if you become disabled. SSI is available for a lot of different reasons. There are elderly who receive SSI because they don't have enough, by way of retirement benefits, to make the payments for their nursing homes and things like that. For people who are under 66 years old, SSI is a supplemental security income and it's a welfare program, in essence, for people who are disabled and haven't been able to work most of their lives. Once again, the government does not want people falling so far underneath the poverty level so that they end up dying destitute and in the streets.