Why is my cat pooping outside of her box? This is the second time...?

My Mom's cat is 12 and does the exact same thing. My Mom keeps her litter box extremely clean! Every time the cat goes in it, my Mom cleans it immediately so it's not that the litter box is not clean. We have no clue why the cat does this but you might consider putting a "potty" pad down and placing the litter box on it so that when the cat does go outside the litter box, at least it will be on the pad.

15 is not so old for a cat. About the pooping - she might be telling you that the box is not clean enough or maybe she wants it moved.

This happened with my 14 year old cat. At the time he was a little "plump" (lol) so I got him a bigger litter box the one with the cover and the problem went away!

Both of you should take your cats to the vet and have them checked for Urinary Tract Infections. It is common in cats, and they will refuse their litter box. In there minds they think the box is hurting them and therefore will go to the bathroom outside of the box rather than in.

my old cat has done that too, the reason she did it was because her box was not clean enough, i found this out because I cleaned it right after she pooped and she was fine with it and stopped doing it. the next time she did it, it was for the same reason

I think she is doing this becuz she does not understand or is a little confused. Like maybe she thinks she is pooping in the box but isn't.