Whether you will be approved for Social Security Disability Insurance (SSDI) benefits or Supplemental Security Income (SSI) benefits depends on how long you worked and paid Social Security taxes and how much you have in income and assets.
When you apply for disability benefits, regardless of which program you applied for, Social Security will decide whether you qualify for SSDI or SSI.
To qualify medically for an SSI payment, you must be over 65, blind, or disabled. Social Security's definition of disabled is the same for SSDI as it is for SSI.
To qualify financially for SSI, your unearned income (money you receive from any source but work) must be less than $710 per month (in some states, this limit is higher). If you work, you can collect SSI if your earned income is less than $1,040 (but your SSI payment will be lowered because of your income). Figuring out the SSI income limit that applies to you can be complicated; see our article on the SSI income limit for more information.
In addition, there is SSI eligibility depends on not having many assets. You can't have more than $2,000 in assets if you are single, $3,000 if you are married. However, Social Security doesn't count property like your house, your car, and your personal belongings in counting assets.
To qualify for SSDI, you must have worked a number of years in a job that paid FICA taxes or have been self-employed and paid SECA taxes. The number of years you have to have worked depends on your age. For the details, see our article on SSDI work requirements.
It's not uncommon for someone to receive both SSDI and SSI. When you collect both, it's called getting "concurrent" benefits. Here's when it happens.
If you did not make much money when you worked, or did not work full-time or year round, your SSDI payment will probably be small. If it would be lower than the SSI payment amount ($710 in 2013) and your other income doesn't put you over the SSI income limit, you will be approved for SSI. Your SSI payment will make up the difference between your SSDI payment and $710 (or whatever the SSI payment is in your state).
The benefit to being on SSDI in addition to SSI is that you'll be eligible for Medicare benefits (rather than just Medicaid benefits) after two years. However, if you collect SSDI in addition to SSI and you make some kind of income, after your first year, you are subject to the substantial gainful activity limit, whereas SSI-only recipients are not. For more information, see our section on returning to work while getting disability.