A: At heart, that boils down to two basic questions. First, you must be eligible to receive SSD benefits because you have worked long enough in a job covered by Social Security, and you paid Social Security taxes on your earnings. Second, you must qualify for SSD benefits because you have an impairment that will, or is expected to, keep you from working for at least a year. The impairment can be a medical condition – such as a terminal or other serious illness – or a disabling injury, which prevents you from working full-time. Some of the rules about this can be different depending on how old you are and the specific type of impairment you have.