Apart from meeting Social Securiy's medical definition of disability -- disability is defined as the inability to do substantial gainful employment -- an applicant must meet the following requirements to qualify for Social Security Disability Insurance (SSDI) benefits.
First, you must not be working at a level that's considered substantial gainful activity. This is generally considered to be $1,040 per month (in 2013). Even if you are working through a great deal of pain, you will be instantly denied if you are making over that amount through work.
Second, you must have the right amount of work credits based on age and the number of years worked. The requirement for workers older than 42 is five to ten years' worth of work credits, depending on the worker's exact age. In addition, five years of work credits must have been earned in the ten years before the onset of disability.
Work credits are earned by working at a job that pays Federal Insurance Contributions Act (FICA) taxes or being self-employed and paying self-employment taxes.
For details on how many credits are needed at various ages, as well as how much income earns a work credit, see our article on work credits for SSDI eligibility.
The requirements for dependents and survivor benefits through Social Security are different. For more information, see our articles on SSDI benefits for family members.
updated by: Beth Laurence, J.D.