My Billy has done that since day 1! He kicks litter out of the box like crazy! I got a hooded lid, though he still kicks litter out, it helps a lot. If you can find one with a door flap on it, that's better, but make sure it's a rubber flap, NOT PLASTIC!!! I bought a plastic one, and it's a piece of, umm.... well, CRAP!
So, anyway, I have not been able to get Billy to quit doing it, so, I got the hooded box, and it lessens it, and I just vaccuum up the litter CONSTANTLY! Though, I do HATE
it when he throws poo out.
Good luck! If you find something that works, let me know!!!