The Social Security Disability Insurance (SSDI) was established in 1954, the purpose of which is to provide income or financial support to those who are not able to work because of disability. It is a federal insurance program wherein a part of the FICA taxes that you pay is set aside and that’s how you have your SSDI. After your retirement age which is 65 years old and above, your SSDI becomes Social Security retirement income. Since disability is the main concern here, we are talking about total disability. Therefore those with partial and short-term disabilities are not eligible for any benefits.