This is a question often posed by new cat owners, who really don’t know answer. If you’re like me, you know you need to do it, but you really don’t want to think about it. The general rule of thumb is to scoop it at least once a day, twice a day preferably and to completely change the litter and sanitize the box weekly or biweekly (if you’re really good about keeping it scooped).
Just think of it this way, you really don’t want to use a dirty toilet, do you? Well, neither does your cat, most cats are very picky and won’t use a dirty box. Some won’t even use it after its been used once! If you cat is like this, you can try using multiple boxes (ideally, you want one box per cat, anyway). You can even try using one of those Rubbermaid storage tubs if your cat needs more room (you can cut a hole in the side of it).