To be eligible for disability benefits, a person must be unable to engage in substantial gainful activity (SGA). If your are working more than part-time hours or earning more than a certain monthly amount than you may be engaging in SGA. Every year Social Security sets the monthly amount for that year that is considered SGA. For 2015, SGA is considered to be $1090 a month for non-blind individuals, and it is $1820 a month for blind individuals.