I've been confused about SSD backpay also. I quit my job in 5/05, filed 1st claim 2/07. Was denied at hearing level in 3/08, then started all over in 6/08. I'm at the reconsideration level at this time. I've read/heard that 1) backpay starts from the time you quit work, 2) 12 months prior to filing date, 3)from the date you filed. I have no idea what the answer is! If anyone has any information on this I would very much appreciate it! Thanks!