www.pro-diem.com

Submitted mine and got it back in 1 day. They charge $50 and that's deductible as well.

7 months of line flying at UPS (all domestic/Hawaii & on leave/training for 5 months) - UPS calculated the total perdiem to be $4058.60

pro-diem calculated it to be $6263.97. Subtract the difference, take 75% of that number. Or use turbotax like I did and they do it for you. Mind you, it's probably not worth it if you don't itemize and have other business deductions (headset, flashlight, etc etc etc). I heard that prodiem will let you know if you don't have enough perdiem $$$ difference to be worth it. Great service.