My kitten is 7 weeks old and I have had him for a week. He has been using his litter box just fine until yesterday. He disappeared in a corner and I find a pile of poopies. I picked it up and put it in his litter box and then put him in it. This first time I punished him (I didn't know this was bad). The next day I go to work and keep him in the bedroom with his litter box and other items. Once I get home I let him roam and he instantly goes to the same spot and poops again! This Time I put it in the box and put him in the box with it without punishing him. I keep his box clean and his food has been moved away from the box. Why would he be pooping out of the box and why would he be doing it in the same spot?
Put a litter box in the spot where he wants to poop. There are a number of reasons he may have chosen that spot, whatever the cause, he likes it so put a litter box there.
General rule of thumb is for every cat, you should have one litter box, plus one. 1 cat = 2 litter boxes. He is telling you where the second one should be. As he grows older you can move it to a different location if this space is not convenient.