With no warning, your cat starts eliminating outside the litter box. There could be several reasons or a combination of reasons. Cats don't do this simply out of spite, the Humane Society says.
A change in routine as well as urinary-tract infections are common causes. Changes include new brands of litter, a new baby, moving the box, relocating or having others move into the home.
Do not move the litter box or change the brand of litter. Only switch brands of litter gradually. Respect the cat’s space and quiet time. Keep the rest of its routine as much as possible.
Try changing the depth of the litter or uncovering it if you’ve recently put a top on it. Cats like sandy material to do their business in, so make sure the litter box stays clean.
Cats will avoid the box because they associate the box with something unpleasant. This can include loud noises or pain of a medical condition. Have the cat examined to rule out medical issues.
After eliminating the above scenarios, if needed, try retraining the cat by placing the box and the cat in a bathroom while away. When the cat deposits in the litter box, reinforce the good habit by giving treats.