I hope I can help this make sense.

Whether he will get backpay depends on his date of disability. For example my date of disability is 8/6/11.

I applied for SSDI in late Feb/early March of 2012. I was approved in April 2012. this is where I get confused and my memory isn't great but I was paid one or two months of back pay since my 5 months were up in February. The reason I'm not positive is I think SSDI pays one month behind (ie the Feb check covers January) so I think I got 2 months backpay and one month regular pay in April 2012 but it may have been one month backpay and one month of pay. I just can't remember anymore.

If you need me to try to explain better let me know. You can also call your local social security office and they can explain. I got a call the day they received my approval and they explained all this. I lived in a very rural county though and in bigger cities that may not be something they do.