I was just wondering about how the SSDI determines what date they will use for back pay purposes if approved. I stopped working in Dec 08. But I was only working part time in 08 and the monthly amount was below the gainfully employed of $960 a month that the SSDI uses. Its looking like I got approved so I was wondering what date they might use. I have read on here that some have been back paid three years. But others say they will only go back 12 months. Anybody have any ideas?