According to Social Security, an individual age 18 and older is "disabled" if he or she has a medically determinable physical or mental impairment which:
*results in the inability to do any substantial gainful activity (SGA):
For activity to be substantial it need not necessarily be performed on a full-time basis; work activity performed on a part-time basis may also be substantial - generally earnings averaging over $1,000 a month. The monthly SGA amount for statutorily blind individuals for 2012 is $1690. For non-blind individuals, the monthly SGA amount for 2012 is $1010. For SSI purposes, the substantial gainful activity provision does not apply.
* can be expected to result in death or has lasted or can be expected to last for a continuous period of not less than 12 months.