It's easy to get frustrated when your cat isn't using the litter box - no one likes a surprise mess.
But before assuming that your cat simply doesn't understand that she should use the litter box, consider that a specific and easy solution could be at hand. Failure to use the litter box could signify a pressing medical problem. Beyond that, check out this list and see if any of these circumstances might apply to you.
It could just be that the litter box has gotten a bit too messy. Remember, cats have a sense of smell that picks up more than ours does. Make sure you're scooping daily, and fully clean the box every few days with mild soap and water so you do not leave behind a harsh chemical smell.
Litter Box Type
It could be that your litter box just isn't the right type for your cat. Follow the rule of thumb that a litter box should be at least 1.5 times the length of your cat. It's important to make sure they have some room to stretch and move around.
"While some cats seem to prefer the privacy of covered boxes, other cats tend to avoid covered boxes altogether," Lindsay Wood behaviorist at the Humane Society of Boulder Valley, explains.
Adding enough litter to the box is important. Make sure it is at least 2 inches deep and that it covers the entire surface.
Litter Box Location
If you have a dog, make sure the litter box is away from anywhere that the dog commonly roams around. You should have at least as many litter boxes as you have cats plus one additional litter box. Even if you have only one cat, she recommends placing a litter box on each floor of your house.
Finally, "It is essential that boxes are placed away from frightening sounds or objects. Washer/dryer or vacuum cleaner locations may be scary."
Remember, if your cat isn't using the litter box, there is hope! Just work together until you find a solution that sticks.