Why is my female spayed cat not using the litter box w/ the male kitten?

This probably has nothing to do with the gender of your new kitten. It's more likely that she doesn't like to share the box.

Get another litter box and if possible put it where she's pooping. Do this as soon as possible before it becomes a habit and will be harder to correct.

You may want to consider putting yet another one in another room.

Your older cat is probably just expressing her distaste for the newcomer. When you have more then one cat, it is best to have seperate litterboxes and seperate food and water dishes so that they can have their own space.

It is also possible that while you are asleep, the kitten is picking on the older cat when she wants to go. If you have a covered litterbox, there is only one way in and out and the kitten may block it while she's in there. It can be enough to keep her from wanting to go in there when you aren't around to "protect" her from kitten.

If you scoop the litterbox only first thing in the morning, it could be that she just doesn't think it's clean enough by nighttime.

Get a second litterbox and make sure at least one of them is the uncovered kind. That should take care of the problem regardless of the cause.

The litterbox rule is # of cats + 1. So, yes, get another box or two right now before the cat gets in the habit of using the floor. Neutering the kitten will not change things at all.

Cats are very picky and set in their ways. She's probably upset that she has to share a litter box with any cat - no matter the sex or being neutered/spayed. Ideally, there should be one litter box to each cat in the house, plus one. I think you could get away with just 2 boxes, though.

A cat will pee on what smells like it's own pee. And poop too! Try taking and old rag and put it in a laundry basket with things the cat has peed on for 1 or 2 days and then wash all but the rag. Put the rag in a bran new litterbox. It will help. Also do not forget to clean the boxes well! But do not wash the rag or take it out till the cat is trained.

Your female cat doesn't like sharing a box you need 2 or even 3 boxes the third is if the other cat uses one of your female cat's litter boxes.And it most likely won't stop after neutering your male cat.My cats do it to and when my female knows my male (neutered) cat uses it she goes in the back yard until we scoop the box.Goodluck! (=^.^=)

Some cats just don't like sharing litterboxes.

Try getting a second litterbox and see if that helps

it could be that the catlitte is not what ur cats like because my cats wont use any litter thats not in tiny pieces and can be scooped